VFD ??

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bure961

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Farmingham, MA
There is a asd EATON svx 9000 for a 75 hp 480v motor / pump, it is in a cabinet with other controls. The asd is rated for 75hp and anytime it runs at a steady 60 hz for a long time it trips out on motor over temperature. The motor does not have the thermistors connected to the asd , wiring was completed by contractor. Motor draws over 99 - 100a, it is rated for 96a . Looks like the contractor did not connect the thermistors on purpose. Can the drive be setup to operate at a lessor frequency then 60hz so it does not trip out ? Any suggestions will be appreciated. Thanks for any help here.
 
bure961 said:
There is a asd EATON svx 9000 for a 75 hp 480v motor / pump, it is in a cabinet with other controls. The asd is rated for 75hp and anytime it runs at a steady 60 hz for a long time it trips out on motor over temperature. The motor does not have the thermistors connected to the asd , wiring was completed by contractor. Motor draws over 99 - 100a, it is rated for 96a . Looks like the contractor did not connect the thermistors on purpose. Can the drive be setup to operate at a lessor frequency then 60hz so it does not trip out ? Any suggestions will be appreciated. Thanks for any help here.
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If there are no connections to the motor thermistors, then the drive is determining that the motor is hot based on the current it is sending to it, because your motor is pulling more than the rated FLC. Someone may have ASSumed that because the motor has a 1.15 Service Factor that this is OK. But in reality, most motor mfrs will tell you that if used on a VFD, 1.15SF motors are de-rated to 1.0SF max., and the VFD's motor temperature algorithm would know this.

I'm not 100% sure on the SV9000, but most likely you can program a current limit into the drive. But what that will do is artificially lower the output speed to keep the current down. That means you will lose pumping capacity. If you are OK with that, contact Eaton and ask how you would do it.

PS: looks as though parameter 1.7 is the Current Limit setting. Set it to 100% and see if that fixes it, assuming you are OK with the lower speed.
 
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