AMRE Safety Seminar 17 April 2012

P.C. Wheeler

KDC West Fatal electrocution presentation

Location 10 Shaft Compressor House

10 Shaft

Compressor

10 Shaft Main

Substation

22

Compressor

house

Background

� During December of 2011 a five yearly scheduled maintenance was performed on a VK 50

Compressor, part of this routine included for the electric motor to be removed and send to an

motor repair company for testing and cleaning.

� On completion of the scheduled activities the motor was returned, installed and connected in

the configuration as originally disconnected.

� On the 2nd January 2012 during start-up of the machine excessive vibration was detected on

the motor, the motor was removed and send back to the repair company.

� On the 3rd January 2012 it was decided to install the spare motor as no estimated time could

33

� On the 3rd January 2012 it was decided to install the spare motor as no estimated time could

have been given on when the motor would be returned to site.

Panel Configuration

The synchronous motor compressor starter panel consist of a four panel board comprising of

the following:

• Auxiliary Feeder

• Main Motor Breaker

• Step 1 Breaker

• Step 2 Breaker

44

This starter panel is fed from the main substation at the shaft ± 300m away from the

compressor house

Synchronous Motor Sarter Panel Configuration

Aux Breaker

Step 1

Breaker

Step 2 BreakerMain Breaker

Incoming Cable

55

Connection Box

Synchronous Motor Sarter Panel Power Diagram

Power

terminations from

Main Substation

66

Events and Actions Leading to the Casualty

� The spare motor was installed and when the connections had to be done it was seen that the

termination configuration was not marked in the same configuration as the one that has been

removed.

� At this stage the Main Motor Circuit Breaker including the Step 1 and Step 2 breakers was

racked out, removed and locked out from the enclosure.

� To ensure correct phasing, it was required to identify of the motor and power leads as the

starting reactor, the electric motor, main breaker and the step 2 breaker are all connected in

series.

77

series.

� The Electrical foreman and two electricians discussed the process of identifying the conductor

connections for the correct termination configuration of the motor, this process required the

back cover plates of the terminations to be opened to execute the testing.

� Both electricians then tested the terminations at the back of the panels with a high voltage

tester and confirmed “dead”.

� The foreman and the electrician were at the back of the Compressor starter panel and the other

electrician at the motor end of the cables.

Events and Actions Leading to the Casualty

� They then continued with the testing as required .The first phase was tested and no continuity

could be established, they proceeded to the centre phase and continuity was established, the

conductor leads and termination was numbered. They returned to the first phase, when the

electrocution occurred.

� First aid in the form of CPR was administrated until the paramedics arrived, the electrician was

taken to hospital and declared dead.

88

Power Circuit Phase configuration diagram

Main

breaker

Step 2

breaker

Step 1

breaker

Starting

Reactor

99

Motor

terminations

Star

Point

Motor termination configuration

1010

Motor

termination

leads

Findings after the accident

� The VT connections were not visible from the position the electrician was in during the

testing operations, due to a small cover plate at the top portion not being removed.

� No warning signs were displayed to warn maintenance staff of live connections from

busbar compartment in the cable compartment.

�

1111

� The VT on the cable compartment was connected with leads through holes in the plate

that separated the cable compartment from the busbar compartment.

� VT connection changes were made to the main Breaker panel as this panel was originally

manufactured to be used as an Eskom Main Incomer.

Back view of Main Breaker

VT

1212

View at back of Main Panel

1313

Motor power

cable

terminations

Top section

cover plate

View with top cover removed

Live VT

connections

1414

Motor power

cable

terminations

View of VT connections to busbar chamber

1515

Conductor leads

to Busbar

chamber

Diagram showing Busbar connected VT

1616

Power flow

direction

Diagram showing Cable connected VT

1717

Power flow

direction

� Inspect the complete compartment for any other “live” sources or terminations.

� Treat all connections as “live” until proven “dead”.

� Check all auxiliary equipment, which forms part of your installation and make sure that it is

included in the risk assessment.

� Document and record all changes and modifications to equipment.

Lessons Learned

� Document and record all changes and modifications to equipment.

� Be meticulous when equipment are used for applications not intended for.

� Display informative signs and notices at all machinery and equipment.

� Regular revisions and improvements on standards and procedures.

1818

Questions?Questions?

1919