SPECIALISTS IN ELECTRO-MECHANICS

A R M A T U R E E L E C T R I C L I M I T E D

100 – 3811 NORTH FRASER WAY, BURNABY, BRITISH COLUMBIA, V5J 5J2

Tel: 604-879-6141 Fax: 604-879-6974

Toll Free: 1-800-539-3556 Toll Free Fax: 877-879-6974

Service Report

Installation of Cool Blue Inductive Absorbers

On

RAM 350HP #C2 Compressor Motor

September 13th, 2016

Service Report - #C2 Compressor Cool Blue Installation (Cont’d)

Overview

We were contacted to perform testing at a food processing plant in Burnaby, BC. Their

350HP Compressor motor has had numerous bearing failures related to fluting of the

bearings produced by common mode currents from the variable frequency drive.

Based on our findings, approval was given to install Cool Blue Inductive Absorbers in the

VFD cabinet to mitigate the present common mode currents.

The bearings on the motor. The bearings were cut in half to investigate the damage. Below is

a photo that clearly shows fluting caused by Electrical Discharge Machining.

Service Report - #C2 Compressor Cool Blue Installation (Cont’d)

Motor Nameplate Information

MAKE RAM Industries

SERIAL # 8133-025894

MODEL # 5AB282

HP 350 RPM 3575 PH 3 HZ 60

VOLTS 460 FLA 379

FRAME 447TS ENCL ODP

MAX AMB 40°C DUTY Cont

NOM EFF 95.8%

DE BEARING 6313 C3

NDE

BEARING 6313 C3

VFD: EATON SPX 9000

(Line and Load Reactors installed)

Installation & Results

VFD was powered down and locked out. Motor leads were removed and initially 4 x M-302

Chokes and 3 x M-613 Differential Line Absorbers were installed over the motor leads.

Service Report - #C2 Compressor Cool Blue Installation (Cont’d)

The VFD was energized and the motor run up to measure the common mode currents using a

Rogowski coil and Scope. Below is a side by side comparison of the initial readings taken on

our first visit and our readings after the inductive absorbers were installed.

Without Cool Blue’s With Cool Blue’s

We can see a dramatic reduction of common mode currents with the inductive absorbers

installed. Initial current readings without the inductive absorbers installed showed an average

of 10 Amps with occasional peaks of 20 Amps. After the installation, we measured peaks of

4 Amps, as well as less frequent occurrences. It was decided to add another choke to further

reduce current as much as possible.

After the 5th choke was added the current was further reduced to 3.5 Amps (Note: The above

capture was taken at a different scale than the previous 2, which is why it appears to show

higher current, but is in fact lower). We had reached maximum effectiveness of the

absorbers, and decided no more chokes would suffice.

Service Report - #C2 Compressor Cool Blue Installation (Cont’d)

To further ensure that this installation was sufficient, we used an SKF Electrical Discharge

Detector, which when held in proximity of a motor’s bearings, will count the number

electrical discharges present over a set time. This test showed zero discharges in the bearings.

EDD Tester on NDE EDD Tester on DE

Conclusion

Cool Blue Inductive Absorbers are the most suitable product on the market to mitigate

Electrical Discharge Machining caused by common mode currents. They are maintenance

free, simple to install and last a lifetime. These results clearly prove their effectiveness in

combatting this phenomenon.

End of Report