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Thread: Closed Transition ATS monthly test in healthcare

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    Closed Transition ATS monthly test in healthcare

    Forgive me if this has been discussed before. I couldn't find it in a search.

    I am in a healthcare setting and we are required to transfer power within 10 seconds which is tested monthly and documented. We can't always meet that due to our closed transition switches. Is there any exceptions to the 10 second rule that would allow for the syncing of the two power sources during testing? We could open normal power and will meet the time. However, there are many instances where it is not practical to do so.

    When we go over, the timing is generally around 11-18 seconds. Any assistance would be appreciated. Thank you

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    Quote Originally Posted by pnunley View Post
    Forgive me if this has been discussed before. I couldn't find it in a search.

    I am in a healthcare setting and we are required to transfer power within 10 seconds which is tested monthly and documented. We can't always meet that due to our closed transition switches. Is there any exceptions to the 10 second rule that would allow for the syncing of the two power sources during testing? We could open normal power and will meet the time. However, there are many instances where it is not practical to do so.

    When we go over, the timing is generally around 11-18 seconds. Any assistance would be appreciated. Thank you
    Out of curiosity I'm guessing you have just 1 genset or if you have multiple in parallel any 1 can carry the 10 second loads and thus be compliant except when doing testing with the closed transition with the POCO?

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    The 10 second rule only applies on actual loss of normal power, I don't think there is any way to test that if the transfer switch is a closed transition switch and both sources are available.
    517.32(B) The life safety and critical branches shall be installed and connected to the alternate power source specified in 517.30(A) and (B) so that all functions specified herein for the life safety and critical branches are automatically restored to operation within 10 seconds after interruption of the normal source. [99:6.4.3.1]
    Don, Illinois
    (All code citations are 2017 unless otherwise noted)

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    ATS Meeting the 10 sec rule in health care environments

    Quote Originally Posted by pnunley View Post
    Forgive me if this has been discussed before. I couldn't find it in a search.

    I am in a healthcare setting and we are required to transfer power within 10 seconds which is tested monthly and documented. We can't always meet that due to our closed transition switches. Is there any exceptions to the 10 second rule that would allow for the syncing of the two power sources during testing? We could open normal power and will meet the time. However, there are many instances where it is not practical to do so.

    When we go over, the timing is generally around 11-18 seconds. Any assistance would be appreciated. Thank you
    First of all, the problem you are experiencing has nothing to do with you having closed transition switches. Whether closed transition (make-before-break) or open transition (break-before-make) design, ATS's employ a feature called an in-phase monitor which is nothing more than a sync check circuit to only allow transfer when both sources are within a certain sync threshold (usually within 10 electrical degrees.) This occurs when the test is performed from the test switch on the controller, what we call a hot bus - hot-bus test. or during a re-transfer after a power failure.
    From what you are describing, when you test from the test switch you cannot meet the 10 sec requirement. This indicate that there is an unusually long sync time before transfer. We find the most common reason for this is that the genset frequency is set either too close or too far away from the utility: 60.00HZ. GE-Zenith recommends a setting of 60.10HZ. We like to see it set at 60.20HZ to allow for speed drift.
    When you test by opening the normal source breaker (which no hospital likes to do, but simulates a real power failure) you meet the 10 second rule. In this type of test, we call a dead bus - hot bus test, your closed transition ATS reverts to a delayed transition ATS with a faster transfer time since there is no sync time in the equation.
    I would recommend calling in your genset vendor to adjust the frequency to 60.20HZ for a faster sync time. Most younger techs aren't aware of this and are prone to setting it dead on 60.00HZ. The other problem is that most gensets come from the factory set at 60.00HZ and either requires a laptop program to make changes or the tech ordering and installing an accessory panel to correct the problem as in the case of Kohler.
    I have attached files from 2 previous jobs that may also help to explain the situation. Good luck.
    Attached Files Attached Files
    Last edited by ATSman; 05-21-19 at 12:08 PM.
    Ifyoucan'texplain itsimply youdon'tunderrstanditwellenough- Albert Einstein

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    Second attached file

    Sorry
    See 2nd file
    Attached Files Attached Files
    Ifyoucan'texplain itsimply youdon'tunderrstanditwellenough- Albert Einstein

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    We do similar testing for a healthcare entity and had a similar issue. What we are now permitted to do is time from when the test switch is activated to the time the emergency source becomes available to the ATS. You might want to run this past the local Department of Health first.

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    Quote Originally Posted by Microwatt View Post
    We do similar testing for a healthcare entity and had a similar issue. What we are now permitted to do is time from when the test switch is activated to the time the emergency source becomes available to the ATS. You might want to run this past the local Department of Health first.
    Yes but that does not comply with the code wording stated in post #3 by Don.
    Ifyoucan'texplain itsimply youdon'tunderrstanditwellenough- Albert Einstein

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    Ifyoucan'texplain itsimply youdon'tunderrstanditwellenough- Albert Einstein

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    Quote Originally Posted by ATSman View Post
    First of all, the problem you are experiencing has nothing to do with you having closed transition switches. Whether closed transition (make-before-break) or open transition (break-before-make) design, ATS's employ a feature called an in-phase monitor which is nothing more than a sync check circuit to only allow transfer when both sources are within a certain sync threshold (usually within 10 electrical degrees.) ....
    I have never run across an open transition ATS that has a sync check. I have programed an extra delay on transfer from generator to utility to prevent possible issues with large motors that are running at the time of transfer.
    Don, Illinois
    (All code citations are 2017 unless otherwise noted)

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    Quote Originally Posted by ATSman View Post
    Yes but that does not comply with the code wording stated in post #3 by Don.
    How so? It doesn't seem to me like "timing the transfer" is part of the required test.

    Anyhow, it seems like if there is an "emergency source available" light on the front of the ATS, measuring how long it takes for that light to come on after the test is initiated would tell you how long the delay would be. If actual power is lost, that's when it would transfer (unless there is an additional delay added into the ATS, but that delay could be added to the time it takes for the light to come on.)

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