Forums » Electrical Engineering

Load Bank

    • 156 posts
    December 22, 2019 2:23 AM PST

    Dear all,

    Normally for emergency power there is a standby generator is considered as a back up. But this generator should be at regular of time to be tested in order to ensure the functionality in emergency case. For this usually a load bank can be rented or bought. But is this allowed per code or standards to test generator live with emergency loads?

    regards

    • 103 posts
    December 22, 2019 2:22 PM PST

    I have never heard of any restrictions on this.

    The emergency load may not test the generators full capacity.


    This post was edited by Steve Ward at December 22, 2019 2:23 PM PST
    • 156 posts
    December 23, 2019 8:54 AM PST

    thanks Steve.

    • 75 posts
    January 5, 2020 12:13 PM PST

    Guiding Standard is NFPA 110, Emergency and Standby Power Systems (This is not a regulation, it is a Standard)

    Here are a couple of pieces:

    8.4.2*   Generator sets in service shall be exercised at least once monthly, for a minimum of 30 minutes, using one of the following methods:

    (1)    Loading    that    maintains    the    minimum    exhaust    gas temperatures as recommended by the manufacturer

    (2)    Under  operating  temperature  conditions  and  at  not  less than 30 percent of the EPS standby nameplate kW rating

    8.4.2.2   Equivalent loads used for testing shall be automatically replaced  with  the  emergency loads  in  case  of  failure  of  the primary source.

     

    The standard contains a lot of information on testing and transfer switches.

    • 156 posts
    January 6, 2020 1:50 PM PST
    Carl Coulter said:

    Guiding Standard is NFPA 110, Emergency and Standby Power Systems (This is not a regulation, it is a Standard)

    Here are a couple of pieces:

    8.4.2*   Generator sets in service shall be exercised at least once monthly, for a minimum of 30 minutes, using one of the following methods:

    (1)    Loading    that    maintains    the    minimum    exhaust    gas temperatures as recommended by the manufacturer

    (2)    Under  operating  temperature  conditions  and  at  not  less than 30 percent of the EPS standby nameplate kW rating

    8.4.2.2   Equivalent loads used for testing shall be automatically replaced  with  the  emergency loads  in  case  of  failure  of  the primary source.

     

    The standard contains a lot of information on testing and transfer switches.

    I agree with you Carl with this. But my question is, for testing generator it is needed usually to have a load bank but how if we test the generator live with emergency loads. Do standards allow this?


    This post was edited by Zone4 Engineer at January 6, 2020 1:51 PM PST
    • 75 posts
    January 6, 2020 2:44 PM PST

    8.4.2.3* Diesel-powered EPS installations that do not meet the requirements of 8.4.2 shall be exercised monthly with the available EPSS load and shall be exercised annually with supplemental loads at not less than 50 percent of the EPS nameplate kW rating for 30 continuous minutes and at not less than 75 percent of the EPS nameplate kW rating for 1 continuous hour for a total test duration of not less than 1.5 continuous hours.

    8.4.9.5.1* For a diesel-powered EPS, loading shall be not less than 30 percent of the nameplate kW rating of the EPS. A supplemental load bank shall be permitted to be used to meet or exceed the 30 percent requirement.

    Here is a couple of more pieces of NFPA 110.

    My translation is, "Use what ever you want.  A Load bank is "permitted" - not mandatory."

    There is a lot of stuff in there about testing the EPS, ATS and other equipment.  You may wish to get a copy.

    • 32 posts
    January 7, 2020 7:18 PM PST

    Per NFPA "monthly test must consist of electrically operating the transfer switch from the normal/standard position to the alternate position and then a return to the normal/standard position [see MSFC(15), Sec. 604.4.1; NFPA 110(10), Sec. 8.4.6.1]."

    it means, you can do the testing of the generator with your emergency load live without load bank.