Does anyone know how to estimate the voltage sag on system voltage upon energizing a transformer, using transformer and system impedance? I am trying to determine a ball park number before going to some type of transient analysis evaluation.
Scenario. Mulitiple generators connected to the grid through a Wye/Wye transformer with a Delta Tertiary (buried).
For a SLG fault on the HV side of the transformer, will the grid contribute SLG current through the transformer?
The SKM model I am running shows a higher SLG current on the HV...
What effect does changing the voltage have on a fixed capacitor? Lets say a substation has a 10MVAR capacitor rated at 34.5kV. If the system voltage goes up or down, how does the MVAR output change?
Is Zero Sequence Voltage detectable through a Delta transformer winding? It appears that the Delta would block it the same as zero sequence current?
Is there any good references on applying zero sequence voltage protection settings?
I am trying to determine why it is not advisable to supply a grounded wye transformer from an ungrounded source? IEEE c57.105-1978 and other literature states this configuration is not advisable.
Does anyone know of references that will help determine apparent soil resistivity as seen by a ground rod encased in bentonite?
IEEE Std 80-2000 states that bentonite has a resistivity of 2.5 ohm*meters, but I would speculate this would not be the apparent resistivity as seen by the electrode?
I have an ungrounded 13.8kV Bus I would like to ground. The 13.8kV bus connects wye connected generators to a Delta - Delta step up transformer for export to the utility. When the generators are disconnected the bus becomes ungrounded. The station service transformer connects to the this...
I am looking for assistance in calculating the 300V Zone of Influence with respect to communications equipment protection at a substation. Does anyone have any references on this?
The local utility will not accept the voltage sag produced by a small (750kW) induction generator being connected to their system. The generator breaker is closed after the unit is rotated to synchronous speed by the prime mover. The current inrush is therefore primarily composed of VARS to...
The local utility will not accept the voltage sag produced by a small (750kW) induction generator being connected to their system. The generator breaker is closed after the unit is rotated to synchronous speed by the prime mover. The current inrush is therefore primarily composed of VARS to...
I am looking for information on the magnetizing inrush of an induction generator started at or just above synchronous speed. The local utility claims that this process will cause excessive voltage sag on the system. Their EMTP model shows an inrush of 5 plus times rated current when the...
I am looking for reference material on ground potential rise. The system I am trying to calculate is an enclosure with communication equipment that is beneath a 25kV distribution line. I want to protect the communication link to a remote generation site with isolators at each end (positron)...
I am installing (3) 2400/120V VT's which will be Y connected, for metering, and have a concern about grounding. Is it good practice to ground the Y point of both high and low voltage windings? Is their a concern of an alternate zero sequence path with the HV grounded? Will leaving the HV Y...
