Would like to start the discussion on selection of motor voltages.
The IEEE 841 standardizes the use of the LV motor for 500hp and below. Say the motor on VFD, the upstream is a breaker as protection. we could go to a much larger size than 500hp as per the conversation with a motor...
we are planning for the field test for our on-site generators prior to arranging for the vendor to perform the start-up tests.
On top of IR Tests we normally carry out, I have the following tests in my mind for the field acceptance tests, which are part of NETA recommendations:
• Stator and...
planning to test on motors for our facility. wonder what would be a cost-effective plant for testing motors.
Other than IR test, should we consider PI test and Dielectric absorbtion test on larger motors particularly? Say PI on MV motors, and Dielectric AB on LV motors larger than 200hp?
thread237-8885
we failed on some 460V Hi-pot test applying 1000V DC. To me 1000v is a proper DC voltage for 460V motor as per IEEE-43 table-1.
Wondering what your thoughts are.
Thanks in advance.
have a question. We purchased a generator with a switchgear ( 4160V ), with two supplies, one is from Utility, the other is from 2x2.5MW generators. The utility is stepped down from 115KV transmission line. Under normal conditions, the generators will be standby. We will need to turn on the...
We are doing a retrofit project. A substation new is being built. There is distance protection on the main incomer, working with utility Distance protection relay to trip on the incoming line fault instantaneously. There is another distance protection relay on one of the outgoing feeder to...
Wonder if there is any particular requirement for the CT on motor differential protection, such as CT accuracy class. To me, there should not be any difference with other overcurrent protections as the CT may see the same external faults as well. Any inputs would be greatly appreciated.
We have an application as described below:
3MVA transformer 13.8KV-4160V. CTs are located on the primary side of the transformer and VT signals come from the secondary side of the transformer (4160V SWGR). We need the program the relay with phase VT ratio. But not quite sure what ratio we...
Hi, Guys,
Does anyone here have experience with Substation voltage transfer, from HV to LV side? We are working on 260KV-25KV Substation and we are trying to figure out the impact of HV design on LV side. Any inputs would be greatly appreciated.
I have used ETAP a lot these years almost exclusively. I have come across the situations when the results do not exactly match what came up from other software which were done by others. The mismatches can be around 10%. The input parameters and calculation fundamentals were the same based on...
Hi, Guys,
As per IEEE519, Isc is maximum short circuit current available at PCC. But the source short circuit current we based on to perform the harmonic analysis should be minimum short circuit level, which represents the worst case senario. Is it correct. This is as per IEEE-519 new revision...
Hi, Guys,
Thinking about something interesting. Upstream short circuit data are required to perform the short crcuit, load flow, motor starting, stabity and harmonic. By default, we have been using 1.5-4 cycle data( interrupting duty) data for years. Is is correct? Any thought are appriated...
I am creating an ETAP grousing model. Received the soil resistivity data with at different depths with different probe spacing. Wonder which numbers should be chosen for two soil layers. Appreciate it for any inputs.
I am trying to set up a syn check parameters for a bus transfer system. Not sure which standard to go with. It is 4160V system. No generators.
The parameters I entered for now are:
Voltage difference 104V;
Frequency difference 0.25Hz;
Frequency hysteresis 0.1Hz;
Phase angle 10 degree.
I...
We are trying to figure out the electrical operational cost for the plant we are designing. The demand load is about 80MW.
The following formula we are using is:
Yearly cost=kWh x hours/year x kWh rate.
The cost for maintenance needs to be provided by the owner.
Did I miss anything?
Any...
A couple of basic questions about Diesel engine Governor control:
The speed droop is adjustable from 0 to 10% or 5% . Is 10% better ?
What is the steady state frequency regulation ? I was told it is 0.33%. It doesn't sound right.
Any input would be appreciated.
I am purchasing a 2.5MW generator recently. Vendor indicates that they the Lead acid battery charger will come with their package. But the client insists on using Ni-Cad Battery since it is their standard. I wonder if there would be any issue if we use NiCad Battery in place of lead acid type...
We are trying to limit Ground potetial rise in mine area to 100V or less. The system ground fault is 500A in 69kv system. The only way of achieving it is to limit Mine Substation resistance to 0.2 Ohms. We have only 2 substaions in mine area, fed from 69KV Substation via overhead lines. We could...
We are connecting 2 co-generators into the utility. The generator output voltage is 13.8KV, the transformer primary voltage is 35kV, which is also Utility voltage. At 35kV level, generators are supplying power to the customer plant. 2 generators are running in parallel with the grid. I wonder...
