CT - Marshallinb Box and Test Terminals

[mikelangel78]

Hello every one,

I've a CT marshalling box that getter 3 CT's (one for each phase).

These box received the wiring cables from each CT secondary terminal box and from that marshalling box it'll be connected the cables that goes to the meters and relays installed in a control house.

To connect the wiring from the outside, the terminals in the marshalling box are located horizontally in a support rail. The terminals are screw clamp and with some kind of slinding bar, PHONEXI CONTACT URTK/S BEN. These sliding bar open from bottom to top. The terminals that received the cables form the CT secondary box have a slinding bar type PHOENIX SB2-RTK/S and the cables that ar going tho the control roomm have a slinding bar type PHOENIX SB4-RTK/S.

From waht I undersatnd this sliding bars installed in the URTK/S terminals have the propose to short-circuit the secondarys of the CT's when they aren't use by a realy or meter, so they avoid that a secondary is opened. And also to test the circuits.

After the CT tests are donne, and if all the secondaries of the CT are used, these sliding bars (SB4) should remain in the open position. Am I right?

Thank you in advanced.

 

[ShooterBoter]

A diagram says more than 1000 words...please draw one.
If the disconnect terminals should be open or closed depends on where in the circuit they are located.

 

[mikelangel78]

Ok. Tomorrow I will place a schematic here.

But the PHONEXI CONTACT URTK/S BEN with PHOENIX SB2 or SB4-RTK/S were use only for testing proposes, right?

Thank you in advanced.

 

[pwrengrds]

Since your doing testing on the CT circuit leave them tightened and in a position so it works and current goes through the circuit.

You should be able to tell how it works by putting it in both positions while injecting current. Visually it should be clear what it does. I can't tell by the cut sheet how it works, it looks like it shorts the CT's at the terminal block.

 

[mikelangel78]

Hello,

Please find attached the diagram were you could see the marshalling box connections.

Could you please help understand the function of the PHOENIX SB2-RTK/S and SB4-RTK/S slide bars?

After the CT tests are donne, and if all the secondaries of the CT are used, these sliding bars should remain in the open position. Am I right?

Thank you

 

[stevenal]

Link page 554

 

[marks1080]

I think you need to reconsider the work you're doing with the level of knowledge on the subject you seem to have. This is not meant to be a mean or offensive reply. These circuits can be very dangerous to work on without the proper knowledge and training. Most people learn this type of work over several years of practical, hands-on experience and working with mentors.

 

[pwrengrds]

That's good advice (from marks1080)it's very expensive to make mistakes in this area, its easy to end up without protection when it's most needed.

 

[mikelangel78]

I agree with you marks1080, and I don't feel confident in perform these tests, but I have to do it, and I don't have nobody in my company to explain me. And studing these the better way I can...

 

[scottf]

If I'm reading the schematic correctly, all of the leads/terminals from the CT are not being brought into the marshalling box, but rather on the terminals corresponding to the ratio being used. I believe it a better practice to land all of the CT terminals/leads in the marshalling box for 2 reasons:

1) If changes to the protection scheme are made, it's much easier if all of the CT secondary leads/terminals are available.

2) When shorting a CT it is ideal to short across the full ratio. As a matter of practice, 50% of the secondary winding, at a minimum, should be shorted. In this case it appears that the 50% rule is being met, but only barely.