Hi All,
When specifying 1MVA transformer or above, do you usually specify its impedance based on short circuit-study performed to determine what the impedance should be, or do you go with OEM recommended standard value for the size transformer and then specify appropriate kAIC and protective...
Hi All,
Are Doble tests effective in evaluating health of GSU transformer windings? Does a transformer need to have its oil drained prior to performing a test(Doble or Megger) to focus on winding insulation, since oil would act as an insulator?
Thank you for your thoughts.
EE
Greetings,
Per IEEE 37-013, manufacturer of HV CBs are required to perform extensive numbers of tests, including short-circuit test, withstand test, etc. How are they able to comply with the standard/spec, and demonstrate that their products meet those requirements considering the high magnitude...
Hi All,
Does anyone know what interrupting medium technology is used for high ampacity generator circuit breakers? I know for 5,000Amps and below typically vacuum is employed, but for high amperage applications, not sure if vacuum is still employed or perhaps SF6 or air blast technology?
Thanks,
EE
Greetings, all
I had a question - does a turbocharged propane engine driven generator needs to be derated for high altitude? I understand the need for derating for high altitude, since the air is less dense at higher elevations and it loses its effectiveness to cool down the engine. But for...
Hello All,
Does a TEFC type motor require electric heaters to keep it warm and dry when the motor is idle? Does it depend upon environment and if the area has high humidity. If there is high humidity, then higher chance of condensation?
Thanks for your thoughts.
Hello All,
What are uses and pros/cons of Alloy type O/L versus Solid state O/L for a single speed motor in the range of 20 HP? Does it depend on environment where a motor is installed? Cost?
Any thoughts on where you'd use either one would be appreciated. My understanding is that both types are...
Greetings All,
What is typical ratio between skW and rated kW of a gas generator? I know that gensets are capable of providing higher starting kVA for motor starting, but do they also provide higher skW for limited time? What is the limiting factor here.. is it the temperature rise on alternator...
Hello All,
Has anyone used a DC to DC converter in the past as battery charger to charge 12VDC battery on a genset? The project I'm working on doesn't have a reliable 120vac supply on site, but there is battery bank that can be used to maintain charge on the generator battery. Looking for 24VDC...
Hello,
For a CT installed indoors in a powerhouse, what is the "typical" or rule-of-thumb life cycle of a CT? What are factors affecting the life expectancy and is it common to see a CT fail in service? Typically, CT's are not maintained, so I was wondering what could be leading up to a...
Hi Gents,
I had a question - is the thermal factor rating on a current transformer refer to continuous or overload capability of an instrument to carry increase in current? For example, if 1000:5 CT has TF of 2.0 at 40 degree C ambient, does this mean that this device can carry 2000Amps...
Hello Gents,
I'm looking at a trend in PI for a water level value and the value is fluctuating below 0 feet and above 0 feet. To me that is strange, I'd expect the trend to be above 0 feet. What can I infer from this trend? When the sensor is reading & reporting a negative value, is that...
Hello Gents,
I notice that in Full Static Excitation schemes, a delta-delta connected PPT is utilized. Why delta-delta type? My thoughts are that to provide higher reliability - if one phase fails, you can still supply AC power to your power bridge converter via open delta connected PPT. Also, a...
Greetings,
Has anyone done offline Potential Transformer burden testing? Is offline PT burden testing more challenging to do than an online testing? Just wanted to hear from your experience.
Thanks,
EE
Hello,
Are there any concerns with locating HPU system and battery bank in the same pre-fab building from safety perspective? Any industry codes one would have to follow?
Thanks,
EE
