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Thread: Timer switch or equal device for 3phase 100 KVA transformer

  1. #1
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    Timer switch or equal device for 3phase 100 KVA transformer

    Hi, I'm looking for ideas to set a transformer works by scheduled times, like install a timer to control it to work as a regular timer do with parking lot lights and others devices. please give an idea since I can not find a timer for a 3phase 200 Amps system.

    thank you

  2. #2
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    Quote Originally Posted by O'donisR View Post
    Hi, I'm looking for ideas to set a transformer works by scheduled times, like install a timer to control it to work as a regular timer do with parking lot lights and others devices. please give an idea since I can not find a timer for a 3phase 200 Amps system.

    thank you
    Well, you're not going to find a 200 amp 3 phase timer, that's for sure. Just use a 200 amp 3 pole contactor controlled by a timer of your choice. It's going to be an expensive contactor and install. Why are you doing this? And are you switching the low side to keep the current down?

  3. #3
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    Quote Originally Posted by texie View Post
    Well, you're not going to find a 200 amp 3 phase timer, that's for sure. Just use a 200 amp 3 pole contactor controlled by a timer of your choice. It's going to be an expensive contactor and install. Why are you doing this? And are you switching the low side to keep the current down?
    I should have said high side-not low side.

  4. #4
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    Yeah, you need a contactor controlled by a time clock, switching the primary is cheaper than switching the secondary, the orange box has been doing it pretty much from their beginning, I can't remember if store 101 was set up this way, but I had done work there many a day.

  5. #5
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    Quote Originally Posted by texie View Post
    Well, you're not going to find a 200 amp 3 phase timer, that's for sure. Just use a 200 amp 3 pole contactor controlled by a timer of your choice. It's going to be an expensive contactor and install. Why are you doing this? And are you switching the low side to keep the current down?

    I need to turn on and off by hours a transformer that is feeding an MRI station so we ca save some money on the electrical bill. Thank for the responses.

  6. #6
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    Quote Originally Posted by O'donisR View Post
    I need to turn on and off by hours a transformer that is feeding an MRI station so we ca save some money on the electrical bill. Thank for the responses.
    No main disconnect on the MRI?
    Deserve's got nothin' to do with it.

  7. #7
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    Quote Originally Posted by O'donisR View Post
    I need to turn on and off by hours a transformer that is feeding an MRI station so we ca save some money on the electrical bill. Thank for the responses.
    Is the MRI vendor OK with an abrupt interuption and reconnection of power to the machine? Also, have you measured the transformer and machine power (not amps) in standby mode to and done the math to see if this is a good idea financially.

  8. #8
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    Quote Originally Posted by O'donisR View Post
    Hi, I'm looking for ideas to set a transformer works by scheduled times, like install a timer to control it to work as a regular timer do with parking lot lights and others devices. please give an idea since I can not find a timer for a 3phase 200 Amps system.

    thank you
    Is the 200A on the secondary side? What is the primary side load.

    What is the load on the primary side. That would be the cheapest side to put the contactor on due to lower current.

    You can probably get a 100A IEC contactor for about $100.

    I would be a little nervous about just shutting an MRI unit off though. I doubt they use all that much power when not actually in use. is there some reason the tech can't just shut off the disconnect when he goes home at the end of the day?
    Bob

  9. #9
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    If for a MRI, not a good idea, can cause voltage spikes that the MRI will not like.

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