200 kw gen set

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LRB

Member
Location
Interior Alaska
I am installing a 200 KW Cat Gen Set that is driving my altimer's. crazy. In the past 45 years I have intalled my share of gen sets but none like this one.This is a portable gen set that came out of a UREA manufacturing plant in Kenia Alaska.The plant is now shut down.The trailer and weather tight enclosure was manufactured for Catipiller by Capital Power Systems in 1995. Can't find Capital Power Systems on the net except for a company in India who makes 1 and 3 phase power meters and I don't think they made this enclosure. I have a 400 A 480V breaker and gen is rated at 250 KVA, 200 KW, 480V 300A. 300 A*1.25= 375 A hence 400 A breaker. Now the hair pulling part:
*** The field terminals are under a plastic cover adjacent to the gen console.
*** The temninal connections are 6" vertically apart, each terminal is at a 45 deg angle and 5 " horozonally from the the side of the enclosure.
***Each phase terminal has a duel 350MCM lug, the T0 terminal has a duel 250 MCM lug.
***The bottom of the terminal enclosure is completely open.
***There is a weather tight door that covers the console and this terminal connection box. The bottom 6" of this door consist's of a rubber flap. It is appearant the intent is to bring the field conductors through this rubber flap on the outer door and then through the open bottom of the terminal connection box.
***There are no provisions for securing conduit or cable.
***I do not see any UL listing on the enclosure. Assuming I can fabricate a means of securing MC cable terminations, I would like to run parallel runs of 3/0. We will have no 277 1 phase loads, but will bond EGC from MC cable and GEC to the T0. GEC will be 1/0 copper run to well casing.
*** I know I have to make the individual parallel sets of phase conductors the same length. Because of the tight constrights of the terminal connection box, I will have to stager the ends of the phase conductors. Do I also have to make A, B, and C phase conductors the same length.
Comments or suggestions? Sorry for the long post.
 

RUWired

Senior Member
Location
Pa.
*** I know I have to make the individual parallel sets of phase conductors the same length. Because of the tight constrights of the terminal connection box, I will have to stager the ends of the phase conductors.
Do I also have to make A, B, and C phase conductors the same length.
.

LRB, i take it your using pvc coated mc cable. Check before ordering that the full size # 3 awg ground is in each cable for the 400 amp breaker.

The conductors are only required to be the same length per phase.

How are you planning on terminating the cables at the gen set. IMO, you might be better off terminating the cables in a tap box suitible for the size and use a type W RHH/RHW single conductor cable from the gen to the tap box.
Rick
 

LRB

Member
Location
Interior Alaska
200 kw gen set

RUWIRED, thanks for the suggestion of type W single conductor cable. Am I correct that this cable is approved to be run from my gen terminal box to the tap box with out additional outer sheath protection? Of course we will use appropriate CG on each end to provide strain relief. Per table 400.5(B) 4/0 single conductor type W is good for 405 amp. Will I still use #3 type W cable for the EGC between gen terminal box and tap box? Any problems with mounting tap box on side of gen enclosure?
 

RUWired

Senior Member
Location
Pa.
Am I correct that this cable is approved to be run from my gen terminal box to the tap box with out additional outer sheath protection?

Table 400.4 list type W cable as a portable cable. So if your hooking up to a portable gen set, should be ok.
LRB said:
Per table 400.5(B) 4/0 single conductor type W is good for 405 amp.
Typically the 90 degree column is used for derating purposes only. You need to use the 60/75 column for your ampere rating depending on the splices in the tap box and the gen set terminals.See article 110.14(C)1.
LRB said:
Will I still use #3 type W cable for the EGC between gen terminal box and tap box? Any problems with mounting tap box on side of gen enclosure?
Table 250.122 lists the ground wire for a 400amp breaker at a # 3 awg. I don't know of any allowances for insulation.
I would'nt mount the tap box on the side of the gen set because the inspector could consider this as permanent wiring.(400.8(1). I would mount the tap box next to the generator on a permanet pedestal type mount, then whip over with the type W cable.(400.7(6),(7),(8).

Rick
 
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