An external braking resistor is required for applications in which the motor must be decelerated quickly and the internal braking resistor cannot absorb the excess braking energy.
The temperature of the braking resistor may exceed 250 °C (482 °F) during operation.
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HOT SURFACES |
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oEnsure that it is not possible to make any contact with a hot braking resistor. oDo not allow flammable or heat-sensitive parts in the immediate vicinity of the braking resistor. oVerify that the heat dissipation is sufficient by performing a test run under maximum load conditions. |
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Failure to follow these instructions can result in death, serious injury, or equipment damage. |
The device monitors the power of the braking resistor. The load on the braking resistor can be read out.
The output for the external braking resistor is short-circuit protected. The drive does not monitor for ground faults of the braking resistor.
Selection of the External Braking Resistor
The rating of an external braking resistor depends on the required peak power and continuous power.
The resistance R is derived from the required peak power and the DC bus voltage.
R = Resistance in Ω
U = Switching threshold for braking resistor V
Pmax = Required peak power in W
If 2 or more braking resistors are connected to one drive, note the following criteria:
oThe total resistance of all connected regenerative resistors must comply with the approved resistance.
oThe braking resistors can be connected in parallel or in series. Only connect braking resistors with identical resistance in parallel in order to evenly distribute the load to the braking resistors.
oThe total continuous power of all connected braking resistors result must be greater than or equal to the required continuous power.
Use only resistors that are specified as braking resistors. For suitable braking resistors, see chapter Accessories and Spare Parts.
Mounting and Commissioning of an External Braking Resistor
A parameter is used to switch between the internal braking resistor and an external braking resistor.
The external braking resistors listed in the Accessories chapter are shipped with an information sheet that provides details on installation.
