I too faced this issue and agree it becomes impractical / hugely expensive if we insist on the margins as required in the quoted specification.
The numerical motor protection relays available in the market take the data that corresponds to 100% voltage at motor terminals and can calculate...
Yes, the voltage is high depending on when the measurement is done. During peak hours, the same could be a lower than 208 Volts.
The distribution transformers in the field are not provided with any feature for on-load correction of output voltage.
The nominal voltage output of the transformer...
IEEE C37.96 Motor protection guide has the following:
"...the time-delay setting should be selected to provide 2-s to 5-s margin above the starting time at rated voltage. Due consideration should be given the integrating effect of the motor-starting current on the relay. When the start time is...
Isochronous mode is used only in a few selected machine in the entire grid. These machines are tasked to bring the frequency to rated.
All the machines are in Droop control mode. Droop control will have a dead band and the control doesn't work within that band. Droop control ensures machines...
You are right, Sir! The symbol indicated suggests it could be temperature sensor (Thermistor with a contact output, I suppose).
Thanks for correcting me.
White PB - it is meant to short the field through resistor for discharging the stored energy in the field winding.
Green plug points are connected to speed switch internally. There will be continuity between the two points when the speed is low / below the internal set point to indicate that the...
I failed to mention that the 0.2s trip may not be relevant for your generator considering the small size and the fact that it cannot impact the grid / power system. You may like to review the protection settings to prevent recurrence.
IEEE Std. C37.102 for Generator Protection has some...
Hydro turbine generators draw about 0.2% of rated power from the power system, when made to motor. This is mentioned in IEEE 242. Loss of excitation causes MVAr to be drawn from the power system to meet the excitation requirements of the generator. This is often a problem to the power system...
You seem to have no other incomers to the busbar other than those from the power plant. So, 51N in the incomers will be required as a back up protection for faults in the outgoing feeders. The other option in case this is to be disabled is the 51N at the upstream of the power plant incomers, if...
67N set to look towards source (could be generator or transformer) is relevant if there is another source in the same system that can feed the fault in the generator / transformer.
In case of simple distribution station such as a transformer connected to a busbar with number of outgoing feeders...
Refer Application Guide for REF615. This guide has Standard configurations section wherein, various possible connections are shown.
You should find a clear answer to your query.
The document is freely downloadable from ABB website.
Could be maloperation due to incorrect directionality. Confirm through test to rule out the possibility.
Could be setting issue - Reverse power protection shall always be time delayed to remain stable during switching incidents. Also, the power pick up setting should not be more sensitive than...
If you keep 4160V winding of LV transformer ungrounded, it behaves like Delta for ground faults on 480V side. Ungrounded Wye means the neutral voltage may rise to Line-to-Ground voltage level when there is an earth fault. But, this may not be a concern as the 410V voltage level the windings...
The Earth switch need not be rated to withstand 738A for a long time as the earth fault protection in switchgear is expected to clear the fault in a matter of couple of seconds.
Short circuit making and carrying capacity of the earth switch is important and in this case, it exceeds the...
PRD is to prevent tank rupture in case of internal fault.
When the transformer is fused on primary side, the speed of fuse operation removes any possibility of tank rupture. So, there is no need to provide PRD.
Internal fuses are better for quick isolation of faulty transformer and are thus...
