RTD and DCT for Generator
RTD and DCT for Generator
(OP)
I was told that problem happens to generator terminal box. The junction box is fitted on the generator and is used for connection for PT-100 Ohm RTD(Winding) and Diffenrential CT. RTD is connected to Monitoring Module while Differential CT(DCT) is connected to Protection relay in switchboard.
When my staff had look at inside of junction box, wires for DCT has been burt and insulation of wires for RTD is melt and shorted. For refenrece the resistance of CT is 0.9 Ohm.
When going thru the above status, does anybody tell me possible reasons I can assume causes problems ?
When my staff had look at inside of junction box, wires for DCT has been burt and insulation of wires for RTD is melt and shorted. For refenrece the resistance of CT is 0.9 Ohm.
When going thru the above status, does anybody tell me possible reasons I can assume causes problems ?






RE: RTD and DCT for Generator
Does the generator still function correctly?
RE: RTD and DCT for Generator
RE: RTD and DCT for Generator
One possibility if the CT secondary normally carries current - i.e. it is not a core balance type - is that a loose terminal in the circuit has caused a high resistance and after that Ohm's Law does the rest through I2R heating.
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If we learn from our mistakes,
I'm getting a great education!
RE: RTD and DCT for Generator
RE: RTD and DCT for Generator
Normally, it is a good engineering practice to have a separate metering/measuring box
RTD's by themselves are of very low power/current consumption and the leads are of high temp rated PTFE insulated.
RE: RTD and DCT for Generator
Sarg
RE: RTD and DCT for Generator
Sarg
RE: RTD and DCT for Generator
I have seen a sustained blue arc on a 480V, 1200A open circuited CT circuit, which burned a hole thru a fiber backboard.
RE: RTD and DCT for Generator
Open-circuit CTs are scary aren't they? I disturbed a bad termination on the secondary of an 18000/5 bus-duct differential CT on a generator auxiliary transformer. The arc was long and powerful. I didn't remember leaping over the handrail of the platform 8' up in the air in my haste to get away from it - my colleagues told abut that afterwards. The terminal rail was severely burnt once we got the generator shut down to take a look.
----------------------------------
If we learn from our mistakes,
I'm getting a great education!
RE: RTD and DCT for Generator
Yes they are..the arc I referred to was also established (or reestablished) when I disturbed the wiring looking for cause for 'false' ground fault trips.
Oh yes, I am glad you survived the jump!