Wire resistors and grid resistors
- Perforated sheet cover (IP20) open to mounting surface
- The short-term load capacity of wire and grid resistors is higher than that of flat-type braking resistors (→ chapter "Braking resistor selection")
- A temperature switch is integrated in the BW..-T braking resistor
- A thermal overcurrent relay is integrated in the BW..-P braking resistor
SEW-EURODRIVE recommends implementing protection against overload for the wire and grid resistors by using a bimetallic relay with trip characteristics of trip class 10 or 10 A (in accordance with EN 60947-4-1). Set the trip current to the value IF (→ following tables).
Do not use electronic or electromagnetic fuses because these can be triggered even in case of short-term excess currents that are still within the tolerance range.
For braking resistors of the BW..-T / BW..-P series, you can connect the integrated temperature sensor or the overcurrent relay using a 2-core, shielded cable as an alternative to a bimetallic relay. The cable entry for BW..-T and BW..-P series braking resistors can be run from the front or the back (→ dimension drawing for BW... / BW..-T / BW..-P braking resistors). Use filler plugs for tapped holes that are not connected.
The surfaces of the resistors get very hot if loaded with PN. Make sure that you select an installation site that will accommodate these high temperatures. Braking resistors are therefore usually mounted on the control cabinet roof.
The performance data listed in the following tables indicate the load capacity of the braking resistors depending on their cyclic duration factor. The cyclic duration factor cdf of the braking resistor is indicated in % and is based on a cycle duration of ≤ 120 s.
