generator - load bank testing

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anbm

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Does the connection from ememergency panel (downstream of E.G.) to the load bank need to be permanent or they only make this connection when they test the generator? How does the test work? can the load bank and building load on at same time? Does anyone has experience on this?

Are there any requirements for load bank location?

Thanks!
 
Typically you would put the load bank connection upstream of the transfer scheme (switch or breakers) so you can load bank the generator while the system loads are being fed normally. If the load bank is downstream of the emergency generator panel, then you must transfer your emergency panel to the generator in order to utilize the load bank.....
 
Clarification: when I wrote emergency panel, I mean the main panel being fed out of genetator and this panel also feeds several ATSs.
 
I've done quite a few connections of this type. There are a few ways it can be accomplished. Typically the testing folks have temp cables thay can connect/lug directly to a breaker in the generator dist panel you describe, depending on the generator size/capacity. For larger generator I typically provide a load bank tap box where connections can be made directly to bus. On some installations you can permenantly install DLO pigtails, which is typically what load bank testing companies will use, with camp-lok connectors. That way connections can be made easily and quicky to test the genset. I would highly recommend this if it is a hospital or facility that will be performing regular load bank tests. You can specify color coded cam-loks to identify phasing to make parallel connections even simpler.... I would recommend providing the load bank feeder breaker with a shunt trip that is wire to an aux contact(s) in transfer switches so when there is a normal power interuption during a load bank test, the load bank breaker is shunt tripped.

http://gencable.com/index.shtml?cables/gencables.htm

http://gencable.com/index.shtml?connector/camlocks.htm
 
loadbank testing

loadbank testing

You need to look at your system single-line diagram to figure out how to use your loadbank.
Depending on your facility, the loadbank may be there for use on other pieces of equipment besides the generator. A logical design will have switching arrangements that allow for testing of the intended equipment while isolating the generator from buiilding load.
And to answer your question about running the facility and the loadbank at the same time - again go back to the single-line diagram and check system capacities. The short answer to that is NO, that the loadbank is likely sized to provide a singificant load to the generator. If you lose Utility power while loadbank testing the generator, you go off the loadbank and provide building power.
John M
 
jimday said:
I've done quite a few connections of this type. There are a few ways it can be accomplished. Typically the testing folks have temp cables thay can connect/lug directly to a breaker in the generator dist panel you describe, depending on the generator size/capacity. For larger generator I typically provide a load bank tap box where connections can be made directly to bus. On some installations you can permenantly install DLO pigtails, which is typically what load bank testing companies will use, with camp-lok connectors. That way connections can be made easily and quicky to test the genset. I would highly recommend this if it is a hospital or facility that will be performing regular load bank tests. You can specify color coded cam-loks to identify phasing to make parallel connections even simpler.... I would recommend providing the load bank feeder breaker with a shunt trip that is wire to an aux contact(s) in transfer switches so when there is a normal power interuption during a load bank test, the load bank breaker is shunt tripped.

http://gencable.com/index.shtml?cables/gencables.htm

http://gencable.com/index.shtml?connector/camlocks.htm
Click to expand...

Thanks for the information, they only do the load bank test when load on ATS is switched to generator, it it correct? So, we actual do not care if normal power is lost or not right since generator already start right? Why do we still need shunt trip CB for load bank? I am confused.
 
If the load test is only performed when the ATS switches are switched to the generator then you need to make sure that the facility loads plus the load bank do not exceed the generator capacity. I would not recommend load bank testing in this manner since testing in this configuration will cause an interuption to the load when swtching to the generator and also when switching back to utility power. It can also introduce stransient voltages when switching load bank steps in and out during testing. Lastly, it will increase the likelyhood of a complete and possibly prolonged outage to critical loads if the generator fails during the load testing. Since the load bank, according to your description, is connected between the generator and the ATS switches, it would make more sense to test the generator when the loads are fed from the normal utility source so they are not interupted by testing. This also gives you a more controlled testing environment.
 
anbm said:
Does the connection from ememergency panel (downstream of E.G.) to the load bank need to be permanent or they only make this connection when they test the generator? How does the test work? can the load bank and building load on at same time? Does anyone has experience on this?

Are there any requirements for load bank location?

Thanks!
Click to expand...

It depends on the site.

Some sites have load bank tap/termination boxes, you bring the load banks to the site connect with temporary leads to the tap box.

Others you have to connect at the generator.

Some sites have permanent load banks with (generally) kirk key interlocks to permit testing of different power systems (generator/UPS).

Most sites where we do load testing we connect at the generator, which is a hassle and in some cases limits returning the generator to standby should there be an outage while loadtesting.
 
mayanees said:
You need to look at your system single-line diagram to figure out how to use your loadbank.
Depending on your facility, the loadbank may be there for use on other pieces of equipment besides the generator. A logical design will have switching arrangements that allow for testing of the intended equipment while isolating the generator from buiilding load.
And to answer your question about running the facility and the loadbank at the same time - again go back to the single-line diagram and check system capacities. The short answer to that is NO, that the loadbank is likely sized to provide a singificant load to the generator. If you lose Utility power while loadbank testing the generator, you go off the loadbank and provide building power.
John M
Click to expand...

If we connect the shunt trip load bank breaker to ATS, which ATS should we connect? There are mpre than one ATS. Should we pick one?
 
Depends on what type of test you are going to do a full load test at 100% of the generator rating, it is unlikely a site with multiple ATS will have one ATS of sufficient capacity to handle 100% load.

We do numerous load test every year (presently completing a 3 week load test of 36 Static PDU's). Each load test is site specific I look at every job first and determine what is need to perform the load test to the specific requirements/specifications of the client.
 
I didn't notice, but is this a new facility? If so then the manufacturer of the generator should be responsible for the test. If it is an existing facility, then you should still contact the company that manufactured the generator and get their input about load testing. The customer that owns the generator should have input on the testing as well. But it all boils down to bringing in an external "load bank" that will be hooked up at the generator on the load side of the main. Usually the generator people do not want to mess with the wiring at the ATS unless it is their equipment. Now some facilities will let you use the "building load" for test purposes., but usually not if they are occupying the building. I have also seen load tests that use a combination of existing building load and the load from an external "load bank", but that requires an exact knowlege of what the building load exactly is so that the added load from the load bank does not overload the generators. As far as duration...I have seen load test take as little as an hour, and some up to 4 hours. Usually it is 2 hours on existing building load and 2 hours on 100% load throught the external load bank.
 
Red Wiggler said:
I didn't notice, but is this a new facility? If so then the manufacturer of the generator should be responsible for the test. If it is an existing facility, then you should still contact the company that manufactured the generator and get their input about load testing.
Click to expand...

Nothing like giving away work or asking your competition in.
 
You would need to look at the available auxillary contacts on your ATS switches. I would tend to want to connect the ATS aux contacts in parallel to the load bank breaker shunt trip. That way any ATS that switches will trip the load bank breaker. I'm assuming all the ATS switches have the "normal" side connected to utility and they would all sense a utility outage at approximately the same time. If the generator is running and they see "good" voltage on the "emergency" side of the the switch they will try to transfer. You may want to "tweak" the timing of the switches, if you can, to let the generator stabalize after "dumping" the load bank. I would also recommend not having simultaneous switching of all thre ATS , but rather "step" load the generator if possible. What type of facility is it?
 
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