Transmitting circuit breaker trip command for 2.5kM distance

[RRaghunath]

When an emergency stop valve operates in our system, the signal generated needs to be conveyed to the 33kV breaker that is about 2.5kM away and tripped.

Can any one please suggest most cost effective method to do this. The operation doesn't prefer the Radio link option.

Thanks in anticipation.

 

[wbd]

Is there any other controls or permissives received from that breaker at this location?
What is the configuration of the power system? Is this breaker a radial feed only from this plant?
Is your plant a generator?
What I'm trying to figure out if there is a way to use a directional current relay at the breaker to trip if current reverses direction.
Other technology may be celluar phone, fiber optics, powerline carrier, microwave, etc.

wbd

 

[RRaghunath]

wbd,

Thanks for the interest shown. The breaker is a radial feed. Could we lay a control cable to convey the trip signal to breaker. What are the problems involved due to the 2.5kM distance involved, like capacitive currents etc.
Can telephone wires be used, if the cable is already existing between the two points.

Thanks

 

[busbar]

Optical fiber is handy stuff, but for metallic pairs between electrical facilities, IEEE 367-1996 may be worthy of review—considering ground-potential rise and induced-voltage levels.

{Description at

http://standards.ieee.org/reading/ieee/std_public/description/comm/367-1996_desc.html

}

 

[dpc]

You could do this with a dc control circuit, and suitable interposing relays at each end.

For telephone circuits, if you are talking about telephone circuits owned by the telephone company, that may be much more complicated, unless you can be assured of dc continuity.

Fiber would be my first choice if installing new material. If you have new digital relaying such as Schweitzer or Multilin, the implementation of transfer trip is pretty straightforward, and very reliable. 2.5 km can be done using multimode fiber and fairly inexpensive fiber transceivers.

As mentioned in previous post, you do need to be concerned with possible ground potential rise and take appropriate precautions. Fiber would eliminate this problem.

 

[RRaghunath]

busbar / dpc,

Thanks for the responses. I agree that fibre is best suited as we do not need to worry about ground potential rise and its effects. But the impression we have is that the terminal end equipment in case of fibre optics is expensive and hence the option cannot be considered unless there are some more uses that the fibres are going to be put to (such as telephony, data communication or SCADA). Correct me if I am wrong.

Coming to using DC control circuit with interposing relays at either end, I would appreciate if you could inform me what care needs to be taken.

Thanks once again for your assistance.

 

[dpc]

The main issue with a dc trip circuit using interposing relays is reliability. You will need to calculate the voltage drop in the control circuit and verify that you will have sufficient voltage to reliably operate the interposing relay. Depending on availability and location of your dc power source, you may not need a separate relay at the stop valve end - just a dry contact to initiate the breaker trip.

But if you go with energize to trip, which is what I would probably want to do, you could consider two separate relays with a one out of two tripping scheme. This would provide some protection against a relay failure. But of course, you have to have reliable dc power available.

You may also want to monitor the coils of your interposing relays using neon lamps or a PLC/relay input.