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Variable Frequency DrivesBypass Options

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Two Contactor Bypass

VFD Bypass Operation

SED2

Drive

Motor

Power Supply

Drive OutputContactor

Bypass Contactor

Mechanically Interlocked

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Three Contactor Bypass

SED2

Drive

Motor

Power Supply

Drive OutputContactor

Bypass Contactor

Mechanically Interlocked

OptionalInputContactor

VFD Bypass Operation

Optional “3rd” drive input contactor electrically isolates the VFD

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Bypass Types – Conventional and Electronic

• Conventional bypass – uses hard-wired electrical components for mechanical bypass control– Switches

– Fuses

– Relays

• Electronic bypass – electronic logic control with simple keypad– Reduced wiring and mechanical

components

– Improved system reliability

– Additional logic features standard

• Interlocked Start

• 2 Safety circuits

• Smoke Purge logic

Electronic Bypass

Conventional Bypass

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SED2 Conventional Bypass

• VFD and Bypass cabinet mounted on common back plate

• Conventional electromechanical control – Indicating lights, selector

switches, relays

• All voltages and HP ratings• Configurations available:

– Disconnect (fused on non- fused)

– NEMA 1 cabinet– 2 or 3 contactor control– manual/auto bypass selection

standard– line/load reactor option– Damper end-switch logic option

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Conventional Bypass Components

Mounting Back Plate

Drive Test Selector

(3 contactor only)

Drive /Off / Bypass

Selector

Bypass ON Indicator

Light

Line Disconnect

Gland Plate

Protectivecover

Conduit Connector

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Conventional Bypass Components

Line reactor (optional)

Input contactor (optional)

Controltransformer

Power fuses (optional)

Line disconnect

Controlrelays

Field wiring terminals

Motoroverload

relay

Bypass contactor

Output contactor

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Conventional Bypass Power Range

HP .5 .75 1 2 2 3 5 7.5 10 15 20 25 30 40 50 60 75 100 125

208/240V

480V

575V

A

B

C D E F

A-F denotes VFD frame size

For more info, see the Bypass menu on this CD

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Electronic Bypass Features

• Easy-touch keypad with status display

• Common remote start/stop• Auto bypass• Essential service mode• Interlock start logic• Disconnect options

– Disconnect– Fused Disconnect– Circuit Breaker

• Two and three contactor models• 6 digital inputs and 6 digital

outputs• Optional line or load reactor

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Electronic Bypass Components

Controltransformer

Outputcontactor

Motoroverload

relay

Line reactor (optional)

Input contactor (optional)

Power fuses (optional)

Line disconnect

Bypass contactor

Fieldwiring

terminals

Electroniccontrol

board

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Electronic Bypass Keypad

• Easy-touch electronic keypad displays status and operating configuration

• Indicates current status with 14 LEDs

• Built -in logic reduces wiring and ensures safe operation

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Electronic Bypass Keypad Features

Indicates that input contactor is closed and drive has power.

Toggling this button opens / closes the input contactor.

Enable closes both drive input and output contactors.

Essential service light flashes when this feature is activated.

Disconnect the motor whether in drive or bypass mode.

Indicates input contactor is closed when on, close pending when flashing.

Enables hand bypass mode.

Enable remote bypass. Bypass light w/ flash. Contactor closes and light comes on when Remote Start input closes.

Auto Bypass light flashes when this feature is activated.

Indicates that one of the safety inputs is open.

Indicates that either the overload input has closed or that the thermal overload has tripped.

Indicates present operational state of interlocked start logic.

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Electronic Bypass Power Range

A-F denotes VFD frame size

For more info, see the Bypass menu on this CD

HP .5 .75 1 2 2 3 5 7.5 10 15 20 25 30 40 50 60 75 100 125

208/240V

480V

575V

A

B

C D E F

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• Low harmonics design• Small enclosure size• Many standard

features• Reduces operating

cost• Low power losses/high

efficiency• Minimal effect on

customer power• Wide power range –

from ½ to 125 HP

Siemens SED2 VFD Advantages