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Author Topic: Brake Resistor Overheat  (Read 86 times)

Moh.Red

  • Electrical Engineer
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Brake Resistor Overheat
« on: August 22, 2019, 09:29:03 AM »
I am wondering what could be reasons for braking resistors overheating!!

We made correct selection of brake resistors as shown in the inverters manual, even though, the brake resistors keep heating.

Can someone help in this? They are installed on a hoist motor of an overhead crane.
~~~ اللهم علمنا ما ينفعنا وانفعنا بما علمتنا ~~~

Johnathan

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Re: Brake Resistor Overheat
« Reply #1 on: October 13, 2019, 03:55:17 PM »
The problem with OH cranes is that no counter weight is installed, this makes the full load to be carried by the motor.

In braking, resistors heat up, if they overheat, this means something is wrong.

- Did you calculate correctly the braking resistors duty cycle?
- If the brake resistors are installed on top of the crane, did you consider a derating due to ambient temperature?
- Do the resistors keep heating when the motor is stopped? sometimes braking units IGBTs have leakage current which keep the resistors heating even when the motor is stopped.

There are many reasons I can mention, you may try increasing the power rating of the resistors (kW not Ohm), this may help.

Good Luck
 :dft012: :045:

 

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