Correct me plz, if i got it wrong;
Generally, there are three possible ways to get summation of 02 circuits for metering or protection purpose;
• DIRECT SUMMATION: Combine the CT secondary circuit of similar phases at the end of your existing secondary circuit (Scan over Partial differential...
Your are right for disabling Instantaneous O/C trip functions of Multifunction relays. On a solidly grounded system 50G element should not trip contactor as well. 51 Element (Normally available as Mechanical Jam)is set to trip contactor. It can be set to initiate alarm as well, on a lower...
Please provide as below for a better analysis of problem;
• specification/Manufacturer/model/rating of Incomer and feeder breakers.
• Specification, setting, input sensing(ZCT or residual connected CT), CT/sensor ratios
• What type of loads are fed by feeder breakers (Motor/transformer/LV...
MANDATORY PROTECTION REQUIREMENTS FOR LV AND MV STARTERS PROTECTED BY MULTIFUNCTION RELAYS
• Thermal O/L Protection (Ansi Device 49): Overload (O/L) protection is always applied to motors to protect them from overheating.(Sends trip signal to contactor or Circuit Breaker)
• Instantaneous Phase...
Further to good comments as mentioned above, NEC Article 430-52 and Table 430-152 dictate phase and ground fault protection for low voltage motor circuits but the type of protective device is a designer’s choice. There are five types, each having different benefits depending on the size of the...
friends,
I want to buy a new PC. Will you please tell me that what are deficenices of CELERON verses INTEL P4 of same speed. My applications are simple as net surfing, MS OFFICE and CAD works.
as i have seen on caterpillar generators, DROOP CT is normally connected in parrallel of droop potentio. If CT polarity is reversed, it will cause to pick excessive reactive power at start and draw a high amount of stator current. If the polarity is ok, You can adjust VAR share by droop ptoentio...
hi friends,
I am not much competent like you all but i have read some where that Asymmetrical current is vector sum of AC and DC components of current at the time of inrush current.Symmetrical current is vector sum is positive sequence, negative sequenceand zero sequence currents.
Jonos. Switch off the main breaker and switch on all distribution breakers and switches. Measure the insualteion resistance with Megger with any cable (Phase or neutral)
Put the clamp meter on cable(with out ground conductor and armoured)you will find the leakage current, but the clamp meter suppose to be very fine. The leakage is almost equal to the phase voltage divided by insulation resistance of distribution circuit for single phase.
Preferred way is to check IR from Switchgear end, as it verifies the integrity of complete loop. Obtained reading is actually almost same as motor IR with out leads because the cables always have a high insulation and IR as well.
Thermal overload devices are not able to respond so quickly(4 cycles). It seems that there is some problem with control supply. Contactors are dropping out at voltage sag, if voltage sag is less than drop out value of contactor, even for one cycle, contactor will drop out. Normal these type of...
