variable speed driven chillers - hvacr expo saudi · pdf filevariable speed . driven chillers...

Arif Hussain National Dev. Manager Chillers
Alsalem Johnson Controls
Variable Speed
Driven Chillers

National Energy Demand
Industrial
Commercial & Government
Residential
up 18%
25%
53%

Why save Power?
Electrical energy efficiency
65 % power loss in the production end in turbines
Only 16 % is left at the consumption end
For every 100 kW input fuel energy, we get 15-20 kW of output energy.
For every 1 kW of power saved at consumer end we save about 6 kW of power at the production end.
Maximum power consumption is in:
Induction machines: fan, pump, compressor
Lighting

How to save Power?
Sources of energy
87 % from fossil fuel
6 % from nuclear
Remaining 7 % from renewable sources: solar, wind etc.
At present rate, by end of 22nd century, non-renewable energy sources will be depleted.
Solution:
Efficient use of available electrical energy
Improve the conversion efficiency
Improve the percentage of renewable energy

Efficient Energy Usage
An enabling technology is Power electronics.
Power electronics is the technology associated with efficient conversion, control, and storage of electric power by semiconductor devices.
Semiconductor devices are the heart of power electronics Variable speed drives hold lot of promise for saving energy

What is a Drive / VFD/ AFD
0
230
460
Volts
Hertz 30 60
460 V
60 Hz = 7.67
V Hz
230 V
60 Hz = 3.83
V Hz
If 230 VAC Power Line:

Basic components of a Drive
Motor
L1
L2
L3
C
L
Input Converter (Diode Bridge)
Output Inverter (IGBTs)
DC Bus (Filter) +
_ + _
+
_
+
_
+ +
_ _

What is a Drive?

VFD Fundamentals
A variable frequency drive converts incoming 60 Hz utility power into DC, then converts to a simulated variable voltage, variable frequency output
60 Hz Power Electrical Energy
Zero - 120 Hz
To Motor
VFD
RECTIFIER (AC - DC)
INVERTER (DC - AC)
AC DC AC
VFD
Zero - 120 Hz 60 Hz
ABB

VFD Fundamentals
RECTIFIER
Positive DC Bus
Negative DC Bus
+
-
INVERTER

RECTIFIER
Positive DC Bus
Negative DC Bus
+
-
INVERTER
VFD Fundamentals

RECTIFIER
Positive DC Bus
Negative DC Bus
+
-
INVERTER
Area Under The Square-Wave Pulses Approximates The Area Under A Sine Wave
Frequency
Volta
ge
VFD Fundamentals

VFD Fundamentals

RECTIFIER
Positive DC Bus
Negative DC Bus
+
-
INVERTER
How Often You Switch From Positive Pulses To Negative Pulses Determines The Frequency Of The Waveform
Frequency
Volta
ge
VFD Fundamentals

Frequency = 30Hz
Frequency = 60Hz
VFD Fundamentals

IGBT
IGBTs turn on and off, timed so that Voltage and Frequency Increase Together, to Increase Motor Speed.
IGBT = Insulated Gate Bipolar Transistor

Non-Linear Loads
Loads which draw non-sinusoidal current from the line: Non-incandescent lighting Computers Uninterruptible power supplies Telecommunications equipment Copy machines Battery chargers Electronic variable speed drives Any load with a solid state AC to DC power converter

Typical AC Drive Configuration
All AC Drives rectify AC to DC, then convert to simulated AC (PWM) to provide the motor Variable voltage and Frequency. The AC to DC conversion generates harmonics.
M 460VAC 3-phase
650VDC
Simulated AC
(PWM)

What is our VSD offering?
Liquid cooled, transistorized, PWM, variable frequency drive (PMW) Definite purpose built Package air cooled screw chiller mounted, wired & tested Liquid cooled for
small size component reliability competitive price tolerance for high ambient.
All drive functions controlled and configured through Control panel. Drive designed for very fast response to changing load.

Chiller VSD details
Cabinet rear showing secondary cooling components
IGBT and motor leads section Internal Cabinet Components
Drive mounted on Chiller

Screws
Screws need constant torque w/speed change

Characteristics
Constant torque with speed change Constant Amps with speed change Horsepower increases with speed. At fixed suction and discharge pressure,
screw draws constant torque and amps.

Liquid Cooling
When NEMA 3R Liquid Cooling offers significant protection
Liquid Cooling allows heat rejection to ambient and eliminates the need for air through the drive.

Internal View of VSD Panel
Cooling glycol water is circulated directly through the drive components for very effective cooling. No power de-rate in hot engine rooms or high altitude.
Cooling Water
to IGBTs

Screw Part Load Efficiency
VSDs are justified by energy savings compared energy wastage with Slide Valve Gives chiller an energy advantage. Takes slide valve out of frequent motion Motors must be chosen CAREFULLY to be suitable for lower speeds. Important to compare at the conditions of the particular application.

VFD Savings Increase at Low Speed
Motors must be selected for VFD service. Slight premium to spec. motors that can run at 100 to 20% speed vs.100 to
50% speed. York compressors all have anti-friction bearings that can run at lower speed in
most applications with R-134a.

VSD Electrical Characteristics
More tons for the same Amps
Smaller breakers and wires on new construction
Increased capacity with existing electrical service
High Short Circuit Withstand Ratings
Zero Inrush No Starting S

variable speed driven chillers - hvacr expo saudi · pdf filevariable speed . driven chillers...

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