Why Electrical Motor Using Terminal Block?

you could double check with these guys here!

http://www.teco.com.au/home

We have a couple of big motors connected this way, but we do not use normal electrical tape to wrap connections, it is 3M high voltage tape.

Yes, he is older than me :)

That is why I ask why some motor have terminal block while other don't. What is the purpose ?

For DOL or 3 terminal motors nowadays some use 3pole+E plug and socket fitted on the terminal box.

I am not sure whether they are doing same for star-delta(six terminal) motors.

Refer www.meltric.com/index-ecm for 200A 4P plug and socket for motor terminal box

while your concern for safety should have been acknowledged... (did you tell your boss before you wrote in this forum?) and can only be commended.... there is the old Army saying... "Follow the last order"

As he is your boss, and I guess that you are not the Senior Engineer yet, you should ask the question at the time, BUT follow the last instruction, as he is the responsible person and if it goes 'pear shaped' it's on his head!

If it does go belly up then you can say.... Nothing! After all he is the boss and will not take kindly to being told he screwed it up.

But, I don't think he got to his position by mistake.. so have you thought he might have something to teach you?

Hello, On my experience I have never seen electrical motors without terminal block. No matter how many KW is. For having terminal blocks on the motor, there is some conditions. 1) Easy to connect and disconnect power supply. 2) Easy to change over from delta to star or vice versa. 3) More safer compare to connect by bolt and isolate by insulation tape. I do that way when the terminal block is broken and I have no choose. Regards,

dear engineer

you will not connect terminal as attached photo, where is supply, you will either connect to star delta or soft starter or vsd , so you will find terminal as it delivered

regards

All the large motors I've done were just like that.Some 12 leads 9 or 6,Generators are similar.Looks like yours is a 6 lead 3phase vertical pump application?.Just be careful about how your connected.Ask your boss if it is "across the line start&run" or is it "Wye start Delta run" and tell him that "I don't assume anything with electrical!".Just do what the chief wants and you can't be wrong,LOL,well 99.9% of the time.Hey it's his baby!

So, did anyone ever use TECO motor? Is this their standard?? Because ABB motor have terminal block. I haven't mention that this is new motor.

I found in the internet about TECO. This is Chinese maker am I wright?. In this case I am shore it's violation from the maker. I can say why mostly makers using Terminal blocks. Respectable makers are like: ABB, Siemens etc. never sells the motor without terminal block. There is one important think regarding terminal block. Once you secure the wires by bolts and isolate by insulation tape, but after some time because of heat the tape can be opened and wires will be naked and you can get short circuit or earth leakage.

TECO is TAIWAN Electric Company. Chinese, Yes. Mainland, NO

All motors have terminal blocks for anchoring the terminals in a place. Some times the terminal blocks get burnt due to loose connections, flash over etc. In the absence of a spare terminal block( it is normal not to stock terminal blocks), as a stop gap arrangement the motor terminals are directly connected to the supply cable with nut bolts. Usually the terminal blocks are replaced at the first opportunity. If the person responsible does no do it, then at a later date some other person may conclude that the motor was supplied without terminal blocks. Best thing is to buy a new terminal block and fix it.

Hmm, I'm a bit confused about this matter. Some expert said okay without terminal some said not okay.

ive been thru that situation as well just follow the simple rule

1. the boss is always right

2. if the boss is wrong, see rule no 1

either a budget constraint or non standard issue but if the workmaship and insulation test is ok the nothing to worry

I do not think it is so much OK or not OK, but that either solution is OK when assembled properly. I have seen far more motors without terminal blocks. In large motors, 300HP and up, I usually see either connections like yours, or the customer specifies bus bar, and usually specifies the number of places for connecting parallel conductors. When you get 3 to 6 parallel conductors for 1000Amps or more then the whole junction box and cable layout becomes very important.

With smaller motors like yours, in North America what you have is typical. You will have a small number of conductors of light weight that are easy to bend and you can stuff the connections into a small connection box. With Terminal boards you need a larger box for mounting the TB's, and allowing for more room for proper exit from the TB to the conduit entry. This has additional cost and room for very little benefit.

I know that different industries usually have de-facto standards that are not mandated by code. It is just a custom, and as a supplier or specifying engineer if you can identify these nuances you have a better chance with that market.

terminal blocks are also costly.

What is the <...cost...> of NOT using them?

Terminal Blocks are very important w.r.t. to following reasons:

1. Easy to Connect and disconnect with proper torque which is not possible in suspended type lug-lug bolted connection.
2. Maintains mechanical clearances between phases in all conditions
3. During short circuit inside motor, it holds the terminal leads in place & absorbs electrodynamic forces generated on terminal leads which otherwise can swing the leads and in severe cases can damage the Junction Box.