Protecting the braking resistors from thermal overload
The braking resistors can be protected against overload and overtemperature with an integrated temperature switch for BW..-T braking resistors and with an external thermal overload relay for BW.. braking resistors.
Circuit 1 | Circuit 1 |
|---|---|
|
|
[1] | Line contactor | [4] | PLC |
[2] | Braking resistor | [5] | Inverter |
[3] | Internal temperature switch or overload relay |
For the sake of clarity, only the integrated temperature switch is visualized in the following graphics. Implementation with an external thermal overload relay is carried out in the same way.
INFORMATION
A PTC braking resistor becomes highly resistive in the event of an overload.
INFORMATION
Flatpack resistors have internal thermal protection (non-replaceable fuse), which interrupts the circuit in the event of an overload and protects against consequential damage. No additional thermal protection is required.
Observe the project planning specifications and the documented assignments of inverter and braking resistor.
Note that with flatpack resistors, the internal thermal protection is only effective at line voltages ≥ 380 V. For line voltages < 380 V, the protection of the braking resistors against overload and overtemperature can only be ensured otherwise, e.g. with a customer-supplied thermal overload relay.
