Variable Speed Drives

Variable Speed Drives:

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Energy Saving in Air Compressors Operation;

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Transmission Losses

Losses due to belt drive = 4 to 6 % due to slip

Losses using Gear Drive = 1 to 2 % due to gaps between tooth.

Losses on Induction motor = Motor efficiency

Example:

friction, heat, eddy current, etc., also known as Power Factor.

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Direct Drive Motor has the highest transmission efficiency

close to 100%

NO load speed (RPM) of electric motor

= (Hz X 60 X 2) / no. of poles

Example:

for a two pole Induction motor.

using formulae:

(Hz X 60 X 2) / 2 = (50 X60 X2)/2 = 3000 rpm.

Example: 

4 pole motor.

( Hz X 60 X 2 ) / 4 = (50 X 60 X2 ) / 4 = 1500 rpm.

Unload power cost:

The most inefficiency operation in a screw air compressors is at unload.

The energy cost you pay without getting any compressed air for usage. It cost you from 30% to 60% FLA when off-load.

Why?

1.

It need oil to circulate the system and some air for pneumatic control system. ( usually 15 psig ). ( oil to lubricate ).

2.

Need to cool the oil and air system.

Based on 2 pole standard motor;

Motor Speed at various frequency : 

20 Hz;

( 20 X 120 X 60 ) / 2 = 1200

25 Hz:

(25 X 120 X 60 ) / 2 = 1500

30 Hz:

( 30 X 120 X 60 ) / 2 = 1800

35 Hz:

( 35 X 120 X 60 ) / 2 = 2100

40 Hz;

( 40 X 120 X 60 ) / 2 = 2400

45 Hz;

( 45 X 120 X 60 ) /2 = 2700

50 Hz;

( 54 X 120 X 60 ) /2 = 3000

HRDF Claimable Training on Air Compressors

Testimonial from Institute Latihan Perindustrian, Jitra, Kedah for conducting a one day workshop on Basic Air Compressor course to teachers and students of the Institute.

From Almig Compressor of Germany. The number Air Compressor Company in Germany, 

The hot bed of compressor manufacturer and air end manufacturing.

You will learn in one year, what others take at least three to five years to learn this much.