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What will happen when we back-charge 220 kV / 20 kV, 500 MVA Generator transformer through 75 MVA, 220/132 kV Grid Auto Transformer. Whether the 75 MVA Grid Auto Transformer can successfully back-charge the 500 MVA Generator transformer? If not, what can be the optimum transformer size to back-charge the 500 MVA Generator transformer.
Is there a way of connecting a three phase pressure control switch on a three phase motor. Also is there a three phase float switch for a three phase submersible pump i know of a single phase switch.
The switch only needs to have a single contact since you use a three-phase motor controller to operate the motor. The switch is wired into the low voltage contactor coil circuit to turn the motor on and off.
1. How does this affect the vector group (YNd1) of the transformer? Will it be changed to YNd11?
2. Will it make any difference as far as the vector group is concerned if instead of phase A and C, phase B and C were swapped on both ends of the transformer?
3. The transformer protection relay is configured for YNd1 group, and it is reading negative phase sequence current (ACB instead of ABC). Changing the vector group configuration will solve the problem?
4. Relay is used for differential protection (percentage differential) of the transformer.
Will this negative phase sequence affect normal operation of the transformer in any way?
In any electrical system, we limit the neutral grounding to 1 or 2 locations at the power source, eg, the star-points of generators or transformers. By keeping the grounded neutrals at the power source, earth leakage current will be flowing radially from the power source to the point of short-circuit at downstream. In this way the direction of earth fault current flow can be easily identified and the earth fault protection relays in the distribution system can easily be coordinated.
Transformers are rated in {VA, kVA, MVA etc.} due to flows of active and reactive power through transformer. In case of transformer we have active power losses as consequence of existence inside resistance of windings (primary and secondary) and existence of active losses of ferromagnetic core and other side we have reactive power losses as consequence of existence losses of magnetic flux (primary and secondary) and existence of reactive power losses of ferromagnetic core.
I am assuming that the trip circuit is floating DC (ungrounded). If so, the moisture could be causing a "sneak" circuit, otherwise known as a "hot short" in the tripping circuit, which essentially bypasses the sensing relay contacts and actuates the tripping relay coil. I would check the cabling between the sensing relay contacts and the trip relay coil and the cabling on the hot side of the sensing relay contacts for insulation problems.
This could be internal corona discharge. The switchgear should be de-energized and closely examined. That means pump out the SF6 and take it apart. Examine all insulating components.
Especially if the sound can be localized to portions of the switchgear which do not have bushings for connection to overhead lines. Even if the sound is in the area of air bushings, deenergizing will allow more in-depth inspection and addressing any sharp edges or cracked insulators, etc.
We are frequently changing tap position of Unit station transformer due to voltage problem. What are the impacts on transformer life and is there any solution to minimize this?
Before breaker's selecting for your electrical system, you need to calculate value of expected short circuit current at the place of breaker's installation. Then you need to calculate value of heat pulse and 1s current (expected value of current during one second). After that you need to calculate power of breaker and finally, after all, you can select appropriate breaker. Values of characteristics of selected breaker need to be higher from calculated values of characteristics of your power system.
Heating and cooling capacity to determine the variable frequency drive output current capability, thus affect its output torque capability.
Carrier Frequency: generally the variable frequency drive rated current is the continuous output value under the highest carrier frequency, the maximum ambient temperature. Reduce carrier frequency won't affect the motor current, but will reduce electronic devices heating.
I have a generator of 3 hp, and it outputs 230 V, and I have a submersible Electric Pump, the motor of which is rated to operate at 460 V, Can I use a step up transformer to increase the voltage output from my generator and power the pump? What more parameters do I need to know of in this case?
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