Grounding points in Allen Bradley Centerline cabinets 1

[1mick1]

Hello all,
I am having trouble finding a suitable method of applying grounding clamps to our centerline motor starters, we have a bank of 4160V 600H.P motors controlled by Allen Bradley Centerline starters 5000V 3PH 1200A 260A max. when we have our motors periodically hi pot tested, we have to apply grounding clamps after suiting up and going through the relavent lock out procedure. The ground point on these cabinets is a small bolt located in the back of the cabinet and is not suited for anything but a spring loaded type "welding" clamp.
Has anybody come across a similar problem or any suggestions as to how we can have a more accesible grounding bar that we can attach a screw type clamp to.

Thank you in advance.

 

[TestBeforeTouch]

Do you need to ground it at all? In order to do a high pot test the equipment cannot be grounded.

If each motor only has one source of power that can be locked out, and it is not on bare overhead lines, then I would consider not grounding.

If grounding must be done to satisfy work rules consider attaching the ground cluster to a nearby building ground.

 

[1mick1]

Hello Test,
Yes we do need to ground the leads from the load side of the starter before we can disconnect the actual motor leads,on this type of starter the motor leads are bolted to the output from the starter in the bottom left of the cabinet,so after we have proved that there is no potential there we apply gronnding clamps to the cabinet ground and then all three phases before removing the outgoing motor leads.

 

[TestBeforeTouch]

Hello 1mick1,

I quess I am asking why you feel the need to ground the leads in order to run the test.

We have a couple of lineups of this gear and we do not disconnect the leads to perform a hi-pot. Our motors are 6900V (same AB starters but they have been labeled for 7200V) and we do not use a test voltage high enough to allow for x-ray production in the vacuum bottle.

On our substation shutdowns we do ground the centerline bus in the incoming compartment.

 

[1mick1]

Thanks test for your input,
I will bring up the need for motor lead disconnection for high pot testing at our next electrical safety meeting.

We still have to find a suitable means for grounding though whenever we have to replace one of these motors, we use splicing kits for the motor terminations and to make sure any potential is discharged from the cables we ground the leads in the starter cabinet.