basics of switchboards - sitrain lms

Basics of SwitchboardsA quickSTEP Online Course

www.usa.siemens.com/step© Siemens industry, Inc.

© Siemens Industry, Inc. 2017

Trademarks

Siemens is a trademark of Siemens AG. Product names mentioned may be trademarks or registered trademarks of their respective companies.

National Electrical Code® and NEC® are registered trademarks of the National Fire Protection Association, Quincy, MA 02169.

NEMA® is a registered trademark and service mark of the National Electrical Manufacturer’s Association, Rosslyn, VA 22209.

Underwriters Laboratories Inc.® and UL® are registered trademarks of Underwriters Laboratories, Inc.,Northbrook, IL 60062-2026.

Other trademarks are the property of their respective owners.

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Course Topics

Welcome to Switchboards. This course covers the following topics:Chapter 1 - Introduction

• Overview• Switchboard Terminology• Switchboard Construction

Chapter 2 – Service Entrance Equipment• Service Section• Switchboard Grounding• Disconnect Devices

Chapter 3 – Siemens Switchboards• SB, RCS, and IPS Switchboards• Other Siemens Switchboards

Final ExamIf you do not have an understanding of basic electrical concepts, you should complete Basics of Electricity before attempting this course.

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Course Objectives

Upon completion of this course you will be able to…• Explain the role of switchboards in an electrical distribution system• Define a switchboard according to the National Electrical Code®• Identify the main parts of a switchboard• Identify various ways power can be brought into a switchboard service section• Explain the difference between hot and cold sequence in relation to current

transformers• Identify the types of main and distribution devices available for Siemens switchboards• Identify the various models of Siemens switchboards

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SITRAIN® Training for Industry

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Residential Power Distribution Systems

Power distribution systems are used in every residential, commercial, and industrial building to safely control the distribution of electrical power throughout the facility.

Most of us are familiar with the power found in the average home. Power, purchased from a utility company, enters the house through a metering device.

The power is then distributed by a load center to various branch circuits for lighting, appliances, and electrical outlets.

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Commercial and Industrial Power Systems

Unlike single-family residential applications, which in most cases use only single phase power, commercial and industrial applications primarily use three-phase power.

Transformers used with three-phase power require three interconnected coils in both the primary and the secondary. These transformers can be connected in either a wye or a delta configuration. The type of transformer and the voltage depend on the requirements of the power company and the needs of the customer.

The accompanying illustration shows the secondary windings of a wye-connected transformer and the secondary windings of a delta-connected transformer. For simplicity, the primary windings are not shown. The majority of applications are wye-connected, but delta-connected commercial and industrial applications are also common.

These are only examples of possible distribution configurations, the specific voltages and configurations vary widely depending upon the application requirements.

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Commercial and Industrial Power Distribution

Power distribution systems used in commercial and industrial facilities are often complex, but, like a residential load center, they are designed to distribute power to devices and systems that perform useful functions.

The power provided to a commercial or industrial facility is much greater than that provided to a home. This power must be divided and safely distributed to various devices and systems with specific current and voltage requirements. Where large amounts of power are handled, switchgear and/or switchboards are used. Where more moderate amounts of power are distributed, panelboards are used.

Good distribution systems don’t just happen. Careful engineering is required to ensure that the distribution system safely and efficiently powers existing loads and has expansion capacity for possible future loads.

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Safe Distribution of Current

The primary role of a switchboard is to divide the incoming main current into smaller currents and safely distribute them as needed. To accomplish this, a switchboard incorporates components that monitor the various currents and provide circuit protection.

Because the voltages and currents vary with the application, the size and current carrying capabilities of switchboard components also vary. In general, the greater the current that a component has to carry, the larger the component.

Other factors that cause switchboard configurations to vary include power company requirements, code requirements, and application needs.

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Small Office Building Example

A small office building, for example, might require 120 volts for interior lighting and receptacles and 208 volts for heating, air conditioning, and exterior lighting. In this example, the utility company supplies a 208/120 volt, three-phase, four-wire (wye-connected) service.

A switchboard divides the power into four feeders for distribution throughout the building. The two outer feeders supply power directly to the 208 volt heating and air conditioning units.

The two inner feeders supply panelboards that divide the feeders into branch circuits. One set of branch circuits supplies power to exterior lighting (208 volts). The second set of branch circuits supplies power to interior lighting and receptacles (120 volts).

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Medium Industrial Plant Example

This example depicts the distribution system for a medium-sized industrial plant. The incoming power is provided by a 480/277 VAC, three-phase, four-wire (wye-connected) system.

The power from the utility company is metered and enters the plant through a distribution switchboard. The switchboard incorporates a main circuit breaker and circuit breakers for each of the three feeders.

The feeder on the left powers a distribution switchboard, which, in turn, feeds a panelboard and a 480 volt, three-phase motor.

The middle feeder powers another switchboard which divides the power into three, three-phase, three-wire circuits. Each circuit feeds a busway run to 480 volt motors.

The feeder on the right supplies 208/120 volt power to panelboards connected to lighting and receptacles.

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Chapter 1 – Introduction

This chapter covers the following topics:

• Overview

• Switchboard Terminology

• Switchboard Construction

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Switchboard Definition

The National Electrical Code® (NEC®) defines a switchboard as a large single panel, frame, or assembly of panels on which are mounted, on the face, back, or both, switches, overcurrent and other protection devices, buses, and usually instruments.

While switchboards and power panelboards perform similar functions, panelboards are accessible only form the front, but some switchboards are accessible from both the front and rear.

The accompanying illustration shows two switchboard sections, an incoming or service section and a distribution section that provides power to feeder and branch circuits. Circuit breakers mounted in these sections provide overcurrent protection. Some switchboards use fusible switches instead of circuit breakers.

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Busses

Switchboards include buses, which are metal bars mounted inside the switchboard, to conduct power to various devices. Bus bars in Siemens switchboards are available in standard tin-plated aluminum or optional tin-plated or silver-plated copper. The default plating for copper is silver.

Standard bus is sized on the basis of heat rise criteria,in accordance with the UL 891 specification. Standard bus bars are sized to limit heat rise to 65ºC above an ambient temperature of 40ºC.

As an option, conductor material can be sized according to the following density limits:

• Copper – 1000 amperes/sq. in.• Aluminum – 750 amperes/sq. in.• Aluminum – 700 amperes/sq.in. (Chicago market)

Tapered-capacity through-bus is standard in Siemens switchboards in accordance with NEMA PB2 and UL891 standards. In compliance with these standards, at each distribution section, the through bus capacity is reduced as load is taken off. The through-bus is tapered to a minimum of one-third of the ampacity of the incoming service mains.

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Metering

Utility MeteringRequirements for power company metering and instrument transformers vary with the utility. Typically, utility company current transformers require a 30 inch high compartment. Switchboard sections that contain utility metering must meet the utility metering compartment specifications.

Customer MeteringA full complement of switchboard instruments with appropriate current transformers, potential transformers, and selector switches are available in all Siemens switchboards. The meters and instrument switches are mounted on hinged panels with potential transformers and fuses mounted on an instrument pan located behind the door. Current transformers are mounted on the main bus or at the load terminals of the branch device and do not require additional unit space.

Power MetersSiemens ACCESS metering solutions offer a complete selection of components and software that can be applied in switchboards. This includes PAC series and 9000 series power meters.

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Switchboard Standards and Ratings

Switchboards are built according to standards set by Underwriters Laboratory (UL 891) and the National Electrical Manufacturers Association (NEMA PB2). Basic requirements for switchboards are also covered in the National Electrical Code®.

When selecting switchboards and overcurrent protection devices, it is important to know the supply voltage, maximum continuous current, and the available fault current.

The voltage rating of a switchboard must be at least equal to the system voltage. The voltage rating can be higher than the system voltage, but never lower.

The ampere rating is the current a switchboard or circuit protection device can carry continuously without deterioration and without exceeding temperature rise limits.

Switchboard bus structures and bracing are designed to withstand a certain amount of overcurrent for a short time so that downstream devices have time to clear the fault. The short circuit withstand rating is the level of fault current a switchboard can withstand for a specified time without sustaining damage.

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Interrupting Ratings

When selecting switchboards and overcurrent protection devices, it is essential to know the available fault current for an application and the interrupting rating for the protective devices intended for use.

NEC® Article 110.9 requires circuit protection equipment to have an interrupting rating sufficient for the available current. There are two ways to achieve this requirement, the full rating method and the series rating method. The accompanying graphic shows an example for each method.

The full rating method requires all circuit protection devices to have an interrupting rating equal to or greater than the available fault current.

The series rating method requires the main circuit protection device to have an interrupting rating equal to or greater than the available fault current, but downstream circuit protection devices connected in series can be rated at lower values.

For the series rating method to be used, the selected series combination of circuit protection devices must have been tested and certified by UL. Each series combination of circuit protection devices has a series connected short circuit rating. For additional information, refer to the panelboards series connected short circuit ratings tables available through the Siemens Industry, Inc. Power Distribution Download Center.

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Chapter 1 – Introduction


• Overview

• Switchboard Terminology

• Switchboard Construction

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Switchboard Frame

The switchboard frame houses and supports the other components. The standard Siemens switchboard frame is 90 inches high, 20 to 46 inches wide, and 20 to 58 inches deep. Width options include 20, 25, 32, 38, and 46 inches. Some Siemens switchboards are available with an optional height of 70 inches and optional depths of 28, 38, 48, and 58 inches.

The modular construction of all Siemens service and distribution sections allows the switchboard to be designed into the building.

Rigid, bolted frames can be shipped individually and moved into the building in sections that are easy to maneuver without special equipment, then quickly assembled in place withminimal labor.

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Bus Bar Phase Arrangements

A bus is a conductor or set of conductors that serves as a common connection for two or more circuits. The NEC requires bus bars to be located so they are free from physical damage and held firmly in place.

NEC® Section 408.3 specifies A-B-C bus phasing from front to back, top to bottom, and left to right (when viewed from the front). There is no industry standard on the location of the neutral.

On a 4-wire delta system, the B phase normally has the higher voltage to ground; however, the C phase may have the higher voltage to ground when metering equipment is present. The bussing that has the higher voltage to ground is marked with orange colored labels.

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Bus Bars and Splice Plates

Vertical bus bars are used to distribute power via overcurrent devices to the load devices. Standard bus bars are made of tin-plated aluminum. Optionally, bus bars made from tin-plated or silver-finished copper are available.

Bus bars may either be temperature rated or current density rated. The current density rating specifies the maximum current per square inch of a bus bar cross section.

The accompanying rear view photo of a switchboard illustrates vertical and horizontal bus bar connections. The vertical phase bus bars appear to be in reverse order because they are viewed from the rear, but are in the proper NEMA order as viewed from the front.

A bus connector makes a mechanical and electrical connection between a vertical bus bar and its corresponding horizontal bus bar.

Splice plates are used to join the horizontal bus bars of adjoining switchboard sections. To make additional distribution sections easier to install when they are needed, the horizontal bus is extended and pre-drilled to accept splice plates.

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Accessible Devices

Components that must be easily accessible to maintenance personnel are mounted on the front of the switchboard. This includes meters and overcurrent protection devices, such as circuit breakers and disconnect switches.

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Assembled Switchboard Section

Cover panels are installed on the switchboard so that no live parts are exposed. The front cover is referred to as the dead front.

The panels are also used as trim to provide a finished look to the switchboard. A product information label identifies the switchboard type, catalog number, and voltage and current ratings.

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Chapter 2 – Service Entrance Equipment


• Service Section

• Switchboard Grounding

• Disconnect Devices

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Service Entrance Equipment

Switchboards are often used as service entrance equipment through which power enters the building.

For example, the accompanying graphic shows a switchboard service section connected to a utility power source. This service section provides power to a switchboard distribution section and, subsequently, to downstream equipment.

Switchboards used as service entrance equipment must be approved and labeled as such. Siemens switchboards are factory labeled as suitable for use as service entrance equipment (SUSE) when specified for service entrance application.

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Six Disconnect Rule

Service entrance conductors must have a readily accessible means of being disconnected from the power supply. The NEC® specifies that for each set of service entrance conductors, no more than six switches or circuit breakers shall be used to disconnect and isolate the service from all other equipment.

In the top example, a single main circuit breaker can disconnect power from all equipment being supplied by the service. In this example, there can be as many feeder and branch disconnect devices as needed.

In the bottom example, a service entrance switchboard without a main disconnect may be equipped with up to six circuit breakers or fusible switches to disconnect power from all equipment supplied by the service.

It is important to note that the six disconnect rule refers to the number of disconnects and not the number of poles. For example. A three-pole circuit breaker or fusible switch counts as one disconnect.

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Service Section

Typical switchboards consist of a service section, also referred to as the main section, and one or more distribution sections.

The service section can be fed directly from the utility transformer. In addition to the main disconnect, the service section usually contains utility or customer metering provisions.

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Top-fed Service Sections

Power can be brought into the switchboard service section from the top or the bottom.

The accompanying graph shows some of the options for a top-fed service section.

Cable can be brought into the top of the switchboard through conduit.

If the cable has a large diameter and more room is needed, a pull box, available in 10” to 30” heights, can be added.

In addition, a bus duct entrance can be provided when a busway connection is needed.

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Bottom-fed Service Sections

The accompanying graphic shows some of the options for a bottom-fed service section.

Cable may enter through a conduit to a disconnect that is fed from the bottom.

If the disconnect is top-fed, a pull section can be added to the side of the service section to pass cable to the top of the switchboard.

Depending on the cable bending space, cable can be connected directly to the lugs or to a cross bus. A cross bus brings the bus connections to the pull section eliminating the need to bend cables.

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Hot and Cold Sequence Metering

Metering can either be hot sequence or cold sequence. This refers to whether or not power is still applied to the utility meter when the main disconnect is switched off.

With hot sequence metering, when the main disconnect is open, power is removed from the load, but power is still applied to the utility meter.

With cold sequence metering, when the main disconnect is open, power is removed from the utility meter and the load.

The accompanying graphic shows hot and cold sequence metering for top-fed and bottom-fed service sections.

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Section Alignment

Some switchboards are rear aligned only. This means that if the depth of the service section is greater than the depth of the distribution sections, the service section extends beyond the front of the distribution sections.

Some switchboards can be front and rear aligned. This means that all sections have the same depth. This may require the use of larger cabinets for the distribution sections.

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Virtual Instructor-led Learning

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• Service Section



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Importance of Grounding

Grounding is an important aspect of any electrical system and must be considered carefully. Any object that is electrically connected to the earth is grounded, but not all ground connections are intentional. A ground connection can occur accidentally as a result of faulty equipment or wiring. Proper intentional grounding, however, is essential to the safe operation of electrical equipment.

There are two primary reasons for intentionally grounding electrical equipment. First, grounding reduces the shock hazard by minimizing the voltage differential between parts of a system. Second, grounding provides a low impedance path to ground for fault current. The lower the impedance, the greater the current in the event of a fault. The greater the current, the faster an overcurrent protection device opens and removes power from the load.

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Service Entrance Grounding

In the accompanying graphic, a switchboard is used as service entrance equipment and is connected to a three-phase, four-wire service. Note that the neutral is grounded at the service entrance. This is accomplished by connecting the neutral to a ground bus bar.

The ground bus bar is connected to the frame of the switchboard and the frame is connected to ground. The neutral disconnect link is left in place to supply a ground connection to downstream loads.

In switchboard service sections to be used as service equipment on 1-phase, 3- wire and 3-phase, 4-wire systems, provisions must be included to isolate the neutral bus from the grounded service neutral. This link can be removed by a maintenance person when checking branch neutral continuity on the load side of the main disconnect.

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Downstream Equipment

The neutral is only connected to ground at the service entrance. When downstream equipment is used, the neutral is isolated in that equipment.

The accompanying graphic shows a service entrance switchboard connected to a downstream section. The neutral of the downstream section is connected to ground through the ground bus bar of the service entrance switchboard. The neutral is not connected to ground in the downstream switchboard.

Notice also that the downstream switchboard does not have a neutral disconnect link. Neutral disconnect links are not needed in switchboards used as non-service entrance equipment.

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Ground Fault Protection

A ground fault is a condition in which current takes an undesirable path to ground. The NEC® requires ground fault protection for most service disconnects and feeder disconnects rated 1000 amps or more on solidly grounded wye systems of more than 150 volts to ground. Ground fault protection may be required or desirable on other systems as well.

Ground fault protection can be provided by a circuit breaker with a ground fault protection feature. For example, the accompanying graphic shows a Siemens WL circuit breaker with a ground fault protection module.

Larger circuit breakers with ground fault protection typically have variable settings for ground fault pick-up, the level of ground fault current required to trip the breaker, and ground fault time delay, the interval of time the breaker will remain closed after a ground fault is sensed. These settings are useful for coordinating protection throughout a facility.

When a fusible switch is used, ground fault protection is provided by a ground fault relay like the one shown in the lower left in the accompanying graphic. This relay also provides ground fault pick-up and delay adjustments.

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Ground Fault Sensing

Ground fault current can be sensed using any of the following methods listed in the accompanying graphic.

The direct method uses a current sensor around a ground conductor. When a line-to-ground fault occurs, current flows through the sensor and the protection equipment responds accordingly.

The zero sequencing method uses a sensor installed around all the circuit conductors, including the neutral on four-wire systems. When there is no ground fault, the vector sum of all the currents is zero. When a ground fault occurs, the protection equipment calculates the level of fault current and responds accordingly.

The residual method requires separate sensors to monitor current each of the three phases (and the neutral on four-wire systems). When there is no ground fault, the vector sum of the currents is zero. If a ground fault occurs, the protection equipment calculates the level of fault current and responds accordingly.

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Direct Method

Zero Sequencing Method

Residual Method


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• Service Section



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Main Devices

Typical switchboards require one or more service main disconnect devices. A main disconnect device is mounted into a service section and feeds one or more distribution sections. In some applications, the main device is located remote from the distribution portion of the equipment. More often, however, the service section is adjacent to one or more distribution sections.

The service section of Siemens switchboards can accommodate a variety of main disconnect devices. Depending on the switchboard model and customer requirements, the main protective device may be any of the following device types: Vacu-Break fusible switch, high contact pressure (HCP) fusible switch, bolted pressure fusible switch (BPS), molded case circuit breaker (MCCB), insulated case circuit breaker (ICCB), or low voltage (LV) power circuit breaker.

All main disconnect devices, except Vacu-Break fusible switches, can be equipped with ground fault protection capability to comply with the NEC® Section 230.95 ground fault protection requirements.

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Branch Devices

Distribution sections of switchboards can accept any combination of molded case circuit breakers and fusible switches.

The accompanying graphic includes two distribution sections, one with molded case circuit breakers and the other with fusible switches. However, as an option, if the system calls for a mixture of these devices, they can be grouped in logical patterns within a single section. This eliminates the need to have a separate section for each type of device and can reduce the total number of sections required.

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Fusible Switches

Three types of fusible switches are available for Siemens switchboards as main or branch devices.

Vacu-Break switches (VBS) and High Contact Pressure (HCP) switches are available with continuous current ratings from 400 to 1200 amperes.

Bolted pressure switches (BPS) with ratings from 800 to 6000 amps offer extremely high interrupting capacity in conjunction with Class L fuses.

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Molded Case Circuit Breakers

Molded case thermal-magnetic circuit breakers are available with continuous current ratings from 15 to 2000 amps with interruption ratings up to 200,000 amp. Interruption ratings are typically tested at 240V, 480V or 600V. These breakers are available with a variety of accessories.

Solid state molded case circuit breakers are available in frame sizes from 150 to 1600 amps. These breakers feature solid-state circuitry which allows for the adjustmentcircuit breaker trip characteristics and are available with options for and ground fault protection, zone selective interlocking, and communication.

Current limiting molded case circuit breakers with continuous current ratings from 400 to 1600 amps with thermal-magnetic protection provide coordinated protection for circuits where extremely high fault currents are possible. Solid state current limiting molded case breakers are also available with continuous current ratings from 400 to 1200 amps.

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WL Circuit Breakers

Siemens WL family of circuit breakers has been designed to address the increasingly demanding requirements of today’s power distribution systems and incorporates the following characteristics: high reliability, compact size, ease of use, modularity of design, flexibility of system communications, and safety-oriented features.

The molded case circuit breakers discussed earlier conform to the UL 489 specification. This specification also covers a category of molded case circuit breaker commonly referred to as an insulated case circuit breaker (ICCB). ICCBs are generally used in switchboards and may be fixed-mounted or drawout-mounted.

Another category of large circuit breaker is the low voltage (LV) power circuit breaker. LV power circuit breakers are generally drawout-mounted and may be used in switchboards or switchgear. LV power circuit breakers intended for the U.S. market conform to American National Standards Institute (ANSI) standards (C37.13, C37.16, C37.17, and C37.50) and National Electrical Manufacturers Association (NEMA) standard SG3. The corresponding UL specification for LV power circuit breakers is UL 1066.

Siemens WL family of circuit breakers includes both ICCBs that conform to the UL 489 specification and LV power circuit breakers that conform to UL 1066 and corresponding ANSI and NEMA specifications. Page 2-22


WL Circuit Breaker Frame Sizes

WL UL 489 circuit breakers have a rated maximum operating voltage of 600 VAC and are available in three frame sizes (1, 2, and 3) with frame ratings from 800 to 5000 amps. All three frame sizes have fixed-mounted and drawout-mounted versions.

WL UL 1066 circuit breakers are generally used in switchgear as drawout-mounted breakers, but may also be used in switchboards. These breakers have a rated maximum operating voltage of 635 VAC and are available in two frame sizes 2 and 3) with frame ratings from 800 to 6000 amps. WL UL 1066 4-pole circuit breakers are also available from 800 to 5000 amps in fixed and drawout-mounted versions.

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NEC® Section 240.87

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New code requires any circuit breaker with a 1200A frame or higher to have some level of arc flash energy reduction by reducing clearing time.

There are seven methods for reducing clearing time:1) Zone Selective Interlocking2) Differential relaying3) Energy-reducing maintenance switch with local status indicator*4) Energy-reducing active arc flash mitigation system5) An instantaneous trip setting that is less than the available arcing current**6) An instantaneous trip override that is less than the available arcing current**7) An approved equivalent means

*Option 3 is one of the most common ways to meet this requirement.** Options 5 and 6 were added in the 2017 code.


NEC® Section 240.87

A circuit breaker’s clearing time is the time it takes for a circuit breaker to sense a fault, open its contacts, and extinguish the arc that occurs as the contacts open.

Since the 2011 NEC®, Section 240.87 has required any circuit breaker that can be set to a continuous current rating of 1200 amps or more to implement an approved means to reduce the circuit breaker’s clearing time. This applies to main, feeder, and branch circuit breakers and includes 1200 amp frame circuit breakers that have been adjusted by a trip unit to a rating lower than 1200 amps. The intent of this requirement is to enhance safety by reducing the arc energy associated with a fault.

One of the approved methods for reducing fault clearing time is zone selective interlocking, which is available as an option for Siemens molded case and WL circuit breakers.

The Dynamic Arc Sentry option available for WL circuit breakers and Sm@rt DAS available for WL and VL circuit breakers complies with another approved method which is referred to as “energy reducing maintenance switching with local status indicator.”

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Zone Selective Interlocking (ZSI)•A method which allows two or more circuit breakers to communicate so that a short circuit or ground fault is cleared by the breaker closest to the fault in the minimum time.

Dynamic Arc Sentry (DAS)

•Available for WL circuit breakers with ETU776.•Allows the circuit breaker to switch parameters from a normal operating mode to a maintenance mode when personnel are near the equipment.

•Maintenance mode parameters can be set to reduce fault clearing time.

Sm@rt DAS

•Available for VL circuit breakers with ETU586 and WL circuit breakers with ETU776.

•Similar features as Dynamic Arc Sentry and can be used with WL and VL circuit breakers.


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Chapter 3 – Siemens Switchboards


• SB, RCS, and IPS Switchboards

• Other Siemens Switchboards

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SB1, SB2, and SB3 Switchboards

Siemens manufactures a variety of switchboards. The type of switchboard that best fits an application is determined by a variety of factors such as space, load, and environment. In addition to meeting present loads, the switchboard should be sized to accommodate potential future load additions.

The devices and buses can be sized to meet anticipated future load demand. Trip units or fuses of lower ratings can be installed to meet present load demands and changed in the future as load increases.

SB1, SB2, and SB3 switchboards are built to UL 891 and NEMA PB-2 standards and provide the rugged construction and service flexibility necessary in systems for industrial plants, high-rise complexes, hospitals, and commercial buildings.

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SB1, SB2 & SB3 Switchboard Features and Ratings

Siemens SB1 switchboards have been designed for the shortest lead times and for applications where floor space is at a premium. The rear of all sections align so the switchboard can be installed against a wall. SB1 switchboards contain front-connected main protective devices and through bus ratings up to 2000 amps and 600 VAC.

SB2 switchboards can have extra depth behind the bussing in each distribution section, can be front and rear aligned, can have density rated bussing, can include insulated case circuit breakers, and can handle up to 4000 amps and 600 VAC.

Siemens SB3 switchboards can handle up to 6000 amps and 600 VAC, are designed for custom options, and can incorporate busway and transformer connections, rear access, and custom utility metering provisions. Page 3-3


SEM3™ Embedded Micro Metering

SEM3™ Embedded Micro Metering Module Technology is a modular metering solution that can be factory installed in SB1, SB2, and SB3 switchboards for energy monitoring, data analysis, and sub billing applications.

The flexible design allows for low, medium, and high density metering requirements to be met efficiently and economically using only a few standardized components.

SEM3 provides an innovative and cost effective metering solution that can be incorporated into existing applications such as power monitoring, building automation, and sub-billing systems. SEM3 also has the flexibility to be installed as a standalone solution with real-time data available from the controller’s standard built-in web pages.

SEM3 has two levels of accuracy to meet the market’s differing requirements and price points. This system makes it easy to meter just the loads needed without the excess hardware and space requirements of traditional solutions.

SEM3 is pre-engineered to integrate into new Siemens panelboards and switchboards but can also be installed in OEM equipment and retrofit applications.

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Sm@rt DAS SB3 Switchboards

Siemens Sm@rt SB3 switchboards incorporate networked intelligent devices and are configured and programmed to communicate with a human machine interface (HMI) for control and monitoring of the switchboard.

The HMI can be integrated into the switchboard or mounted in a remote panel. Use of a remote HMI provides the added advantage of control and monitoring from outside the arc flash hazard boundary.

Typical equipment associated with a Sm@rt DAS SB3 switchboard includes a SIMATIC S7 PLC connected to activation switches and indicator lights and electronic trip unit circuit breakers, including WL circuit breakers with Dynamic Arc Sentry (DAS) capability. The PLC can be configured to communicate with a supervisory control system for additional monitoring and control.

A variety of optional features are available to enhance the capabilities of the system.

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Rear Connected Switchboards (RCS)

Siemens Rear Connected Switchboards (RCS) differ from front-connected SB1, SB2, and SB3 switchboards primarily in the distribution sections. RCS distribution section branch feeders are individually mounted and access to the outgoing cable terminals is from the rear of the section. Bus bar extensions from the feeder devices are run to the rear of the section stopping before the conduit area for easy access and cable connection. An optional cable management system can be provided to secure the outgoing cables.

The front and rear of all sections align and are designed for mounting away from the wall. Enclosures can be indoor (NEMA 1) or outdoor (NEMA 3R) construction.

RCS switchboards accommodate requirements up to 6000 amps and 600 VAC. The main bus can have a 400 to 6000 amp rating. Main, tie, and branch devices are available in ampere ratings up to 6000 amps.

RCS switchboards use WL insulated case and/or low-voltage power circuit breakers with draw-out mountings. Features include high breaker density, 100 kA standard short circuit bus bracing, and three levels of horizontal bus. Options include insulated/isolated bus, Dynamic Arc Flash Sentry, ModBus communication, and intelligent power monitoring. Page 3-6


Integrated Power System Switchboards

Siemens integrated power systems (IPS) switchboards integrate multiple pieces of electrical distribution equipment into a single assembly. The modular design of the IPS switchboard allows it to be combined with standard service entrance or distribution switchboards. IPS switchboards can be cable or bus connected to existing switchboard lineups. IPS switchboards offer the following advantages.

Reduced installation timeIPS switchboards arrive at a jobsite with the components factory installed and wired. The result is significantly reduced installation time and cost.

Reduced Space Requirements By integrating components that are typically individually mounted, the IPS switchboard can reduce the space requirements for typical electrical equipment installation by up to 40%.

Reduced Installation RiskIPS switchboards are assembled at Siemens manufacturing plants with meticulous attention to details and strict testing procedures. Using IPS switchboards eliminates risks, enabling projects to come in on time and on budget.

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IPS Switchboards – Commonly Mounted Equipment

IPS Switchboard Features• All standard SB1, SB2, and SB3

switchboard features• Lighting panelboards• Distribution transformers• Half high distribution chassis• Individually mounted breakers• Auxiliary sections for ACCESS

power monitoring, surge protection devices, contactors, relays, time clocks, motor starters, customer equipment, etc.

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Simulators

Engineered to provide a real-world experience, Siemens simulators are fully functional, ready-to-use systemsavailable in a variety of configurations.

System-level design makes the simulators an invaluable tool for program testing and debugging, reinforcing learning, shop floor troubleshooting, and more. With portable construction and hard-shell cases, they can be easily transported. Custom-built systems are also available.


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Chapter 3 – Siemens Switchboards


• SB, RCS, and IPS Switchboards

• Other Siemens Switchboards

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Generator Ready Switchboards

Siemens Generator Ready quick connect switchboards meet the market need for quick connection of a generator for temporary back-up power. The most common applications of these switchboards are retail stores with perishable goods, nursing homes, and hospitals. However, these switchboards are also suitable for many other commercial applications where a power outage can result in increased cost or loss of revenue.

Features• All standard SB1, SB2, and SB3 switchboard features• Crouse-Hinds quick-connect Cam-Locks for a quick primary

connection method• Standard mechanical lugs suitable for Type W welding cable for

a secondary connection• NEMA 1 and NEMA 3R enclosures• Trap door on NEMA 3R enclosure to maintain rating with cables

connected• Labeled phases and ground connections• Bus connection between generator breaker and plug-in quick

connects• Mechanical interlocking with normal breaker• Removable screw cover for covering quick-connects when not

in use• Stand alone unit or hard bussed in a standard switchboard

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Generator Ready Switchboard Construction

Generator Breaker CompartmentThe generator breaker can be connected to the normal main switchboard by cable in retrofit applications or hard bussed in new construction applications. The generator breaker is key-interlocked with the main breaker in the normal switchboard lineup. The switchboard can be rated as suitable for use as service entrance equipment.

Quick-Connect CompartmentCrouse-Hinds quick-connect Cam-Locks are provided in a compartment with a screw cover that can be easily removed to gain access to the quick-connects. One end of each quick-connect is connected to the switchboard and the other end attaches to the generator cable. In addition to the quick-connects, standard mechanical lugs are provided as a secondary method of connection. The mechanical lugs are rated for Type W welding cable, which is common in generator applications.

Generator ConnectionThe switchboard generator breaker can be connected to a new or existing switchboard lineup either by cable or hard bussing.

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Solar Ready Switchboards

Siemens solar ready switchboards provide a solution for both AC and DC commercial solar applications.

In addition to all standard switchboard features, optional viewing windows are also available for an additional level of safety when working with inverter inputs. Siemens switchboards meet all utility and code requirements.

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Skinny Main and Branch WL Switchboard Sections

Siemens skinny main and branch WL sections provide a solution for electrical rooms with a limited footprint.

In addition to all our standard switchboard features, the skinny main switchboard features a hinged auxiliary compartment for easy access to lugs and through bus connections.

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4-High WL Switchboard Sections

Siemens 4-high WL switchboard sections provide a solution for electrical rooms with a limited footprint.

In addition to all our standard switchboard features, the WL switchboard design incorporates the high-end features of WL circuit breakers in our most compact footprint.

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Commercial Multi-Metering Switchboards

Siemens commercial multi-metering switchboards are designed for applications where multiple utility meters are required. These applications include shopping centers, office buildings, and other buildings with multiple tenants.

Siemens offers two types of multi-metering switchboards, SMM and MMS. SMM switchboards are designed to meet EUSERC specifications. MMS switchboards provide a high-quality, multi-metering solution for areas where EUSERC compliance is not necessary.

Features• Up to 4000 ampere main bus rating• Up to 600 VAC• Bus bracing up to 200KAIC• Type 1 and Type 3R enclosures• Standard hot sequence metering with optional cold• sequence metering• 100, 200 or 320 ampere meter sockets• Sockets include lever type manual bypass• Ring-less type meter cover design• All other SB1, SB2 & SB3 switchboard features

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Stock Service Entrance Switchboards

Siemens stock service entrance switchboards are designed as stock units to meet the fast delivery needs of the market. All of Siemens stock switchboards are suitable for use as service entrance equipment. These switchboards combine utility metering provisions and a main service disconnect that can either be a Vacu-Break fusible switch or a molded case circuit breaker.

Stock switchboards have many applications, some of themost common include: retail stores, office buildings, small factories, commercial stores and shopping centers.

Individual Product LinesSuper Blue Pennant• Specifically designed to meet EUSERC requirements• Provision for EUSERC utility metering• Main fusible switch or circuit breaker• Optional distribution panelBCT Service Cubicle• Provision for utility metering (non-EUSERC)• Main molded case circuit breakerSCT Service Cubicle• Provision for utility metering (non-EUSERC)• Main Vacu-Break fusible switch

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SITRAIN® Training for Industry

Online Self-paced Learning – Programs with maximum flexibility so students can easily fit courses into their busy schedules

Virtual Instructor-led Learning - Classroom lectures delivered in the convenience of your home or office

Classroom Learning - Expert and professional instructors, proven courseware, and quality workstations combine for the most effective classroom experience possible at your facility or ours

How-to Video Library - Quick, affordable, task-based learning options for a broad range of automation topics for training or purchase

Simulators - World-class simulation systems available for training or purchase


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SITRAIN World

From the basics to advanced specialist skills, Siemens SITRAIN courses deliver extensive expertise directly from the manufacturer and encompass the entire spectrum of Siemens Industry products and systems.

Worldwide, SITRAIN courses are available in over 200 locations in over 60 countries.

For additional information including a SITRAIN world map and SITRAIN contacts worldwide: http://sitrain.automation.siemens.com/sitrainworld/Default.aspx

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Course Completion

This course covered the following topics:Chapter 1 - Introduction

• Overview• Switchboard Terminology• Switchboard Construction


• Service Section• Switchboard Grounding• Disconnect Devices

Chapter 3 – Siemens Switchboards• SB, RCS, and IPS Switchboards• Other Siemens Switchboards

This course has covered the topics shown on the left. Thank you for your efforts. You can complete this course by taking the final exam and scoring at least 70%.

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basics of switchboards - sitrain lms

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