Portable Generator Systems

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I have been asked to design a standby system for our local power company. They have purchased a portable rated for 800A 208/120v 3Ph. They want to use the Gen to backup any of there 3 offices located in different towns. Town 1 being fairly easy I can install a Manual transfer switch on the load side of the 400A disconnect located on the exterior of the building, and set up some (2) 200A cord and plug connections. Towns 2 and 3 are a little more difficult, being 800A and 1500A services. My question is can I install a transfer switch upstream of the meter and would this involve installing another fused disconnect upstream of the transfer switches? Any advice and other option would be greatly appreciated!
 

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
Took, welocme to the forum! :)

My question is can I install a transfer switch upstream of the meter and would this involve installing another fused disconnect upstream of the transfer switches?
Yes, if the POCO is okay with it, but remember the meter will spin during genny use, and yes, unless the transfer switch is service rated.
 
Thank for the reply, so am I ok to install 200A cord and plug devices in parallel to achieve my desired amperage at each location. My concern was safety of the crew plugging in the system from the portable gen to the transfer switch and back feeding their cords.
 

Cold Fusion

Senior Member
Location
way north
I have been asked to design a standby system for our local power company. They have purchased a portable rated for 800A 208/120v 3Ph. They want to use the Gen to backup any of there 3 offices located in different towns. Town 1 being fairly easy I can install a Manual transfer switch on the load side of the 400A disconnect located on the exterior of the building, and set up some (2) 200A cord and plug connections. ...
Took -
That 800A FLC generator, I suspect it has a 1000A main CB. If so:

q1 What is the over current protection for your parallel cords?

q2 Is the feed from the gen to the transfer sw 5W?

... Towns 2 and 3 are a little more difficult, being 800A and 1500A services. My question is can I install a transfer switch upstream of the meter and would this involve installing another fused disconnect upstream of the transfer switches? Any advice and other option would be greatly appreciated!

As Larry said, you can do it, but I don't know if it is a good idea.

If you install the transfer sw above the meter, and you put in a fused disconnect ahead of the transfer sw, for the utiity feed, what is your plan to change the existing service disconnect from 4W to 5W?

cf
 
so am I ok to install 200A cord and plug devices in parallel to achieve my desired amperage at each location. My concern was safety of the crew plugging in the system from the portable gen to the transfer switch and back feeding their cords.

Assuming that you're trying to feed an entire building on one ATS-
Unless you go with "oil rig" connectors, I think the biggest one you'll commonly find is 400a (camlock e1016 style or equiv. single cond.), so paralleling is going to happen. Likewise, to achieve 800a, you'll need to parallel conductors anyway. I wouldn't try to use multi-conductor cable for 200a unless you have some gorillas to handle it. (You could use 200a pin/sleeve connectors with 5 single leads into them. Check to see if they're rated for it.) I'd use single conductor type SC, it's rated for this use.

Oh, also, if you're feeding multiple 200a connectors off an 800a generator, very likely you'll need OCP for each one at the generator. Not sure whether you could apply the tap rules to this, but probably not.

This is definitely something that I wouldn't send a random crew to connect. It needs someone that has been trained to do so and understands what can happen if, say, the parallel conductors are crossed at one end. (When an old friend at New England Tel (now retired) set up emergency generator connections at transmission facilities, he'd install lugs-n-studs instead of connectors. Because it was more that just plugging in, the power techs made the connections and he was much more confident that it would be correct.)

Written procedures- write up the procedure to connect and disconnect and post it everywhere, esp as the buildings are different. Building 'A' might only need two or three sets of connections, building 'B' might need six.

Be careful where the SBJ is located...
 
Took -
That 800A FLC generator, I suspect it has a 1000A main CB. If so:

q1 What is the over current protection for your parallel cords?

q2 Is the feed from the gen to the transfer sw 5W?

cf

The FLC is accually around 900A something and has a 1200A main. I am open to options as far as the wire type. Also concerned about OCP for the cables running in parallel, is it necessary since the are not in conduit to have protection on each one?
 
Assuming that you're trying to feed an entire building on one ATS-
Unless you go with "oil rig" connectors, I think the biggest one you'll commonly find is 400a (camlock e1016 style or equiv. single cond.), so paralleling is going to happen. Likewise, to achieve 800a, you'll need to parallel conductors anyway. I wouldn't try to use multi-conductor cable for 200a unless you have some gorillas to handle it. (You could use 200a pin/sleeve connectors with 5 single leads into them. Check to see if they're rated for it.) I'd use single conductor type SC, it's rated for this use.

Oh, also, if you're feeding multiple 200a connectors off an 800a generator, very likely you'll need OCP for each one at the generator. Not sure whether you could apply the tap rules to this, but probably not.

This is definitely something that I wouldn't send a random crew to connect. It needs someone that has been trained to do so and understands what can happen if, say, the parallel conductors are crossed at one end. (When an old friend at New England Tel (now retired) set up emergency generator connections at transmission facilities, he'd install lugs-n-studs instead of connectors. Because it was more that just plugging in, the power techs made the connections and he was much more confident that it would be correct.)

Written procedures- write up the procedure to connect and disconnect and post it everywhere, esp as the buildings are different. Building 'A' might only need two or three sets of connections, building 'B' might need six.

Be careful where the SBJ is located...
I like the thought about the line crew just running the cables from lug to lug it would require mor thought with less chance of mixing them up. Do you think it would be wise to install fused disconnects on the generator its self to provide OCP on the parallel conductors. I also like the idea of single conductor SC.
 
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