Hi all,
A synchronous motor 11 kV and 2.8 MW (DOL contactor) employs a series impedance (inductor) to limit the starting current during startup. After a few seconds, a bypass contactor is activated to bypass the impedance. The DC excitation is applied following the bypass.
A manufacturer asks...
Hi all,
We are scheduled to perform a factory acceptance test at a manufacturer for a new slip-ring induction 11kV (3000Kw, 180A, 990 rpm) motor. I am particularly interested in gaining more insight into the following tests:
Withstand voltage tests: According to the IEC standard, the test...
Hi all,
Has anyone used a current clamp meter for high voltages (6 kV or higher)?
I came across some models online claiming to support up to 7000 V, but I'm not sure if they can truly measure current in high-voltage cables.
Hi all,
When we have to use residual earth protection 51N and 67N and what's the difference?
Is it true that 67N is only used on the incomers and 51N on the outgoing feeders?
Hi all,
A slip-ring induction motor of 2700kW and 165A (stator) 990rpm, 1340V and 1250A (rotor). When we start the motor with no mechanical load (uncoupled motor so motor turns alone) we have 40A current and it's normal but what about the speed in this case, should we have a lower speed when...
Hi all,
I'd like to know few things on how large synchronous motor works. I saw one 11kV 2.8MW with components such : Power source (from MV contactor), large inductor (for starting) and motor excitation system
- From what i understand the large inductor is used as current filter, can anybody...
Hi all,
I have 2 wound rotor motors each of 22 kW.
We shorted the rotors at the slip ring so that it would behave like a squirrel cage one then used VFD for each.
It worked well. It is now one year since and so far no problems have been recorded.
My question is if i can replace the 22 kW wound...
Hi all,
I have few questions, would like to understand about thermocouple sensors working:
1- We have some thermoucouple sensors (type T), the distance between sensors and transmitters is about 200m. As the thermoucouple output is few millivolts, is this distance can causes drop voltage and...
Hi all,
I'm looking for Mini CIRCUIT BREAKER 1 POLE 2A with aux contacts (1NO and 1NC for example)
I searched but i can't find one with aux contacts, can you suggest some models?
Hi all,
We recently installed a Liquid Resistance Starter in replacement of grid rotor resistance for 2 motors 11kV/2700kW.
With grid rotor resistance, we could make a rotor to earth insulation test using Megohmmeter insulation tester (we test rotor+cables+resistances connected together). The...
