Recently, while performing a reactive test on our generator, our 40-2 loss of excitation relay tripped before we reached our generator capability curve. We backed off the MVAR, the relay cleared. We increased the MVA, and the relay tripped again at approximately the same point (0.828 pu)...
submonkey: I used R=V^2/P and X=V^2/Q, S=460*1.88=864.8, Q=sqrt(S^2-P^2)=833.6 R=(460)^2/230 and X=(460)^2/833.6
jghrist: It's a 13,300V primary, 120/240V secondary. During operation, there is a 0.9ohm resistor on the secondary. During the impedance test, the secondary was shorted, so it does...
Do small transformers have more resistance than reactance?
I'm trying to calculate the reactance and resistance of my 25KVA generator neutral grounding transformer. There is no nameplate, and the impedance test data shows Impedance Amps = 1.88, Impedance Watts = 230, Impedance Volts = 460...
You can use a main lug panel when you have an upstream breaker to protect the panel. If you do not have an upstream breaker, you should use the main circuit breaker panel.
We had a problem with our boiler feed pumps shutting down on a spurious excessive vibration. Eventually, we traced it down to whenever an operator keyed a radio near the pump, it caused a spike in the vibration signal. We bought shielded cable and no longer have this problem.
It sounds to...
It might just be a naming convention. Like byrdj said, "black start" just means that I can start it up without utility grid power. I would consider all diesel generators to be "black start capable" because I haven't met one yet that required AC power to be started.
But federal regulations in...
In addition to what others have posted, think of the transformer inrush, which will be more than your FLA. Your conductor should be sized to handle your inrush current. Otherwise, you may damage your conductor the first time you energize the transformer. Also, if your conductor is undersized...
The different voltages are not really the issue. Like dpc said, within certain limits, different voltage cables can be mixed. However, the NEC does require the separation of power cables and instrumentation/communication cables. I think this is more of an AC problem, since AC power cables can...
For electrical construction, you want to consult the NEC instead of the NFPA 70. The NEC Article 250 deals with grounding and bonding.
With that said, the answer to "Would this be an approved grounding method" is probably not. Article 250.52 lists electrodes permitted for grounding as (1)...
Are power triangles proportional through per unit?
I'm trying to calculate a neutral grounding transformer's p.u. reactance and resistance. I've been given the amps, watts, and volts from the transformer impedance test, and I know the rated voltage, so I can calculate the p.u. impedance. Since...
What are you trying to do? PF correction would not be made to a wind turbine. PF correction is made to loads, and a wind turbine is a generator. With that said, since a wind turbine outputs DC which is inverted into AC, the inverter will handle the power factor of any supplied loads.
You reference the NEC, so I assume you intend to abide by it. So, tagging along with what davidbeach said before, you cannot parallel these conductors and be in compliance with the NEC. Section 310.10(H)(1) states conductors "shall be permitted to be connected in parallel (electrically joined...
The NEC allows for engineered calculations. For conductors rated 2001 to 35,000 Volts, there is an equation under 310.60(D). For conductors rated 0-2000 Volts, there is an equation under 310.15(C). Both equations allow you to calculate the ampacity of the conductor with your own value of...
I've only seen this used for a "constant MVA" approach to short circuit rating. This approach was dropped a while ago. Basically, the symmetrical interrupting capability of a breaker was increased as the voltage was decreased (hence constant MVA) down to the minimum voltage. Below the minimum...
Determining electrical operating costs can be very simple or very complex, depending on the equipment. Obviously, you will need to determine the power cost associated with operating the equipment. You probably also want to consider the maintenance costs associated with maintaining the...
