connecting a 500 HP 460V motor

[idresu]

I am from Europe and am used to all of our motor T-lead connections being made via a connection block inside the 'peckerhead'. To me this method is quicker and a lot more reliable as it also rules out the human error associated with having to bolt and wrap the leads. The question I have though is this, which would be better and more reliable for large motors 460V 500HP, and does anyone know what the largest size of motor is that is supplied with the terminal block style connector.

T1 T2 T3
---------------------------
| o o o |
| |
| |
| o o o |
---------------------------
U1 V1 W1

Thanks

 

[electricpete]

does anyone know what the largest size of motor is that is supplied with the terminal block style connector.

We have 8000hp 13.2kv motor with a bus mounted on standoff insulators (one per phase). The T-lead and field leads both connect to the phase bus. I don't think there is a size limit.

If having bus prevents you from having to tape, that's definitely good. But that depends on size/space/clearance considerations of the terminal box.

I think there can be more potential for human error when we connect T-leads to field leads without benefit of mounting point/terminal block. One thing I have seen is humongous oversized field leads (sized for voltage drop) connected to tiny T-leads of a sealed motor, which created stress that bent the T-leads sharply where they passed through the sealing epoxy barier from motor into term box. This created a crack in the T-lead insulation at that point. Perhaps it could have been avoided with better workmanship, but it's a challenge.


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(2B)+(2B)' ?

 

[electricpete]

I forgot to mention, the motor T-leads were also cut very short in the case I mentioned, which aggravated the situation of creating mechanical stress concentration on the T-leads where they come through the barrier.

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(2B)+(2B)' ?

 

[7anoter4]

electricpete, I think idresu is speaking about Power Ring Connector as per Tyco:

http://www.te.com/catalog/bin/TE.Co...=255&BML=10576,17844&LG=1&PG=1&IDS=381507&N=1

I don't think it is usually in US and I don't think it is so good. As you can see it is only for low voltage and maximum for 6 awg. Of course, 500 hp it is far from this!
:.

 

[electricpete]

Thanks 7anoter4.

I was discussing the basic distinction of whether the field power lead connects directly to the motor lead, or whether motor supplier gives you something else to connect to in the terminal box, in order to facilitate the process.

That something else can be a good feature as discussed above. But if the thing they give you to connect to is a piece of junk, that is also a concern. Probably the word "block" in the original post suggests a device similar to what you linked. I'm not too familiar with that type of thing being used in motor terminal boxes, have only seen similar things in switchgear on relays etc.


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(2B)+(2B)' ?