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hi buzzp, yes the failed samples were taken first. but no oil was bleeded out. yes even we feel that it might have failed due to air. regards,

thanks jnims, now i understand why the inspector did not accept the test.by the way our test booth does not have the facility to apply 100% rated current. is there any alternate method you can sugest??? or else we are doooomed......

thanks jnims, does that mean that for measuring load loss, rated current is to be applied and for winding temp rise test not below 85% is to be applied? is my intrepretation of the ansi std correct??? regards,

hi all, The local specification for outdoor control cabinet states that "The interiors of unventilated metal cabinets (exclusive of internal heat-producing sources) can reach 56°C. The components and its accessories, including cabinets and junction boxes, shall be designed accordingly" The...

hi jnims, as mentioned in C57.12.90-1999, Clause 11.5.2.1 When test equipment limitations dictate, operating at a value lower than rated current, but not less than 85% of rated current, is permissible. does this applies for load loss measurement also or only for winding temperature rise...

Hi all, i was involved with testing of a 7.5 MVA, 13.8kV-4.16kV transformer. the following points were noted. 1,The Liquid-Temp Indicator (thermometer)installed was with capillary and not direct stem type. Does ANSI C57.12.10 states that the Liquid-Temp Indicator (thermometer) shall be direct...

We have a requirement for the 480V switchears and Motor control centres to have rating for 65kA (symmetrical) short circuit current and the main bus bracing for 100kA momentary short circuit current (Asymmetrical). I would like to know if the vendor provided 65kA (symmetrical) short circuit...

some continuous some intermittant..there are 5 different feeders on this MCC.

controlgear is a term used for motor control centres(MCC).

with all the sugestions posted i am convinced that the feeder breaker to the fire pump should be rated for 1500A with short circuit and groung fault protection. the only doubt still remaining is the rating of the controlgear,1200 or 1500A!!!!!!!!!!

From purely a technical basis, the continuous current rating of the MCC bus is not really a factor, since the locked rotor current will stop once the fire pump motor either accelerates or burns up. for the above said comment wouldnt it be better if the mcc bus is capable of withstanding the...

i have a controlgear rated for 1200A,480v. one of the feeder is a fire water pump.having a FLA of 240A(locked rotor current 1500A Approx. i am extracting the local std requirement for fire pump unit package. "QUOTE" The protection schemes for Fire Pump Unit (FPU) packages shall comply...

i have a controlgear rated for 1200A,480v. one of the feeder is a fire water pump.having a FLA of 240A(locked rotor current 1500A Approx. i am extracting the local std requirement for fire pump unit package. "QUOTE" The protection schemes for Fire Pump Unit (FPU) packages shall comply...

thanks for the reply in fact the fire water pump is fed by a 480v motor control centre. the motor control centre is being fed from the 480v switchgear. i would also like to know if the The fire pump supply must be capable of providing locked-rotor current indefinitely i.e 1500A. should the Motor...

i have a controlgear rated for 1200A,480v. one of the feeder is a fire water pump.having a FLA of 240A(locked rotor current 1500A Approx. i am extracting the local std requirement for fire pump unit package. "QUOTE" The protection schemes for Fire Pump Unit (FPU) packages shall comply...

let me tell you the exact situation i have a control gear with motor starters using 239 multilin relays .the secondary of the phase ct's used have x1 & x2. x1 is the ungrounded circuit conductor and x2 is the grounded circuit conductor. the color coding used for the x1 is white and for x2 is...

interesting finding peebee..you are right i am living in saudi arabia. most of the stds/codes used here are all american.but the local std states that the wire insulation COLOR for neutral should be white. i am confused in regards to the CT's and PT's. can the 'XO' of the Ct be considered as...

our local standard requires neutral wire colour code to be white.can somebody tell me if i have to follow this for the neutral of CT's and PT's used for metering and protection.

the xfmr does have a pressure relive device.but now the question is regarding the vacuum bleeder.what are the possibilities of a vacuum being created inside a sealed type transformer.

with reference to the above standard,i have a 2500kva , 13.8kv,480v xfmr with power BIL. para 5.7.2 of ansi c57.12.10 states that a pressure vacuum bleeder is to be provided for XFMR rated 2500kva and above with power BIL. my transformer is sealed type. is the pressure/vacuum bleeder required...