Good morning. I have a 2.5mw, 12.5kv/480-277v transformer with a %Z of 6.10. My understanding is the that maximum available fault on the secondary would be The transformers full load current divided by %z (Ifla/%z). The utility has provided a secondary symmetrical fault current of 56398amps...
Good Morning. The client has a Rockwell Automation Centerline 2100 series 480v/2000A MCC that is labeled as a 3phase 3wire Solidly grounded neutral (honestly have never herd of 3p/3w/solid neutral ground). The MCC is being fed from a 480V/277 wye xmfr whose neutral point is grounded at the...
Hello. I am trying to size the primary fuse for 3.75mva-33kv/480v transformer. The NEC allows primary only protection at 250% for supervised installations which is my situation. My FLA is 65amps. When looking into fuse vendor data (ie., S&C, cutler hammer, little fuse, etc...) many list a...
We have an inline pump with a 150HP/3 phase 460V, 165A nameplate vertical motor, Delta Start, Delta Run (6 leads). The pump and motor were out of service for over a year and recently serviced and moved to a new installation at a different facility. The new installation is a similar application...
I have an 2500A, 480V distribution panel (call it DS1) with a 800A current limiting fuse. The fuse feeds an 800A, 480V MLO panel (Call it Panel P1). P1 has a 225A branch feeding another 480V MLO panel. The 800A Fuse and the 225A coordinate under overload but not fault currents. There are not...
In the past year we have have had (2) 150hp 480V motor windings burn up. The motors are on dedicated circuits and each had a few hundred hours run time prior to burning up. The Motors are started by a VFD which is set up as a soft starter that ramps the motor to full speed in about 15 seconds...
Does anyone know of the code requirement (if any) for leak testing of steam heat trace piping?
I have a 6" #6oil pipeline (800ft) that I am heat tracing with 1" sch80 steel pipe. Normal operating pressure in the winter would be around 20psig. If the regulator fails the steam pipe could see...
We have a fuel oil pumping system consisting of two centrifugal pumps each driven by 100HP motor. Both mother feeders are identical each with the exact same soft starter. One of the motors had to be replaced. The replacement motor is a high efficiency motor and now keeps tripping the soft...
The contractor has installed a water service butterfly valve in a compressed air system application. The valve is in a bypass line around an air filter bank and will be normally closed during operation to force the air through the filters. Can I use this valve even though it is not rated for...
My client has a 255 Ton chiller with a 795 gpm condensing loop to a cooling tower. The cooling tower is rated for 95F EWT & 85F LWT. The Chiller Condensing loop is rated for 85F EWT & 95LWT. The client has a well that he would like to use for the condensing cooling as opposed to the cooling...
Client currently has a 52kPPh and 26kPPh BW watertube D style, dual fuel (2oil & NG) boilers operating at 125psi. Site steam load being reduced to 20psi with load between 5kPPh and 15kpph peak. Is anyone aware of any concerns to the boilers with operating these boilers at reduced pressure. For...
Do the load tables in the SJI handbook already have a safety factor built in. I am trying to determin the loading of a roof and have 22H6 joist at 6ft spacing. I I use the live load (228plf) for this joist at 30ft. span this gives me 38psf. Would this be the loading or should I add safety to...
