CT wiring
- Thread starter bnewport
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bphgravity
Senior Member
- Location
- Florida
Re: CT wiring
I have never heard of twisting the secondary leads from a current transformer. Is this stated or implied by the manufacturers instructions?
I have never heard of twisting the secondary leads from a current transformer. Is this stated or implied by the manufacturers instructions?
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
Re: CT wiring
The output of a current transformer is AC and usually 5A, so twisting the wires provides no benefit.
The only reason I have ever seen for twisting CT wires is for appearance. Also, twisted (as opposed to cable tied) wires are easier to route (pull) through switchgear.
The output of a current transformer is AC and usually 5A, so twisting the wires provides no benefit.
The only reason I have ever seen for twisting CT wires is for appearance. Also, twisted (as opposed to cable tied) wires are easier to route (pull) through switchgear.
brian john
Senior Member
- Location
- Leesburg, VA
Re: CT wiring
CT's commonly utilized with GF protection systems are specified to be installed twisted. These CT's are actually listed as Current Sensors and have a much lower output (higher ratio). Check the specifications as mentioned.
CT's commonly utilized with GF protection systems are specified to be installed twisted. These CT's are actually listed as Current Sensors and have a much lower output (higher ratio). Check the specifications as mentioned.
Re: CT wiring
We are installing sub metering for a multi tenent building, for billing purposes. The main breaker is ground fault protected, and after further inspection, only the neutral CT leads are twisted, the phases are not. Thanks for the quick reply. Does anyone know the reasoning behind twisting the neutral leads?
We are installing sub metering for a multi tenent building, for billing purposes. The main breaker is ground fault protected, and after further inspection, only the neutral CT leads are twisted, the phases are not. Thanks for the quick reply. Does anyone know the reasoning behind twisting the neutral leads?
wanderer20001us
Senior Member
Re: CT wiring
Twisting the conductors lowers the impedence of the circuit under high current conditions (like during a fault) and helps ensure proper relay accuracy and response.
Twisting the conductors lowers the impedence of the circuit under high current conditions (like during a fault) and helps ensure proper relay accuracy and response.
Re: CT wiring
posted May 07, 2004 07:40 AM
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Twisting the conductors lowers the impedence of the circuit under high current conditions (like during a fault) and helps ensure proper relay accuracy and response.
Because of mutual inductance?
posted May 07, 2004 07:40 AM
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Twisting the conductors lowers the impedence of the circuit under high current conditions (like during a fault) and helps ensure proper relay accuracy and response.
Because of mutual inductance?
Ed MacLaren
Senior Member
Re: CT wiring
Twisting the wires keeps them closer to each other which maximixes the amount of flux cancellation, lowering the inductive reactance component of the impedance.
Ed
Twisting the wires keeps them closer to each other which maximixes the amount of flux cancellation, lowering the inductive reactance component of the impedance.
Ed
Re: CT wiring
What voltage rating should the wire insulation have from the ct's to the metering cabinet? The service is 277/480 WYE. Some say 600V, others say the voltage will increase proportional to the ct ratio... who is correct? If the ct's are always shorted or connected to a burden, is the higher voltage wire insulation even an issue?
Bryan
What voltage rating should the wire insulation have from the ct's to the metering cabinet? The service is 277/480 WYE. Some say 600V, others say the voltage will increase proportional to the ct ratio... who is correct? If the ct's are always shorted or connected to a burden, is the higher voltage wire insulation even an issue?
Bryan
bphgravity
Senior Member
- Location
- Florida
Re: CT wiring
600-volt rated conductors will be fine. The only potential danger of significant voltage rise on the transformer secondary is if the leads open while current flows on metered conductors.
600-volt rated conductors will be fine. The only potential danger of significant voltage rise on the transformer secondary is if the leads open while current flows on metered conductors.
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