Toshiba G7 manual Dynamic Braking Resistor Wire/Cable Specifications

Dynamic Braking Resistor Wire/Cable Specifications

When using a Dynamic Braking Resistor (DBR), use thermal protection and an input contactor that will open the input 3-phase power circuit to the ASD in the event that a DBR over-temperature condition occurs. In the event of a power source over-voltage condition or an ASD failure the input contactor will prevent hazardous DBR temperatures.

Because the heat generated by the DBR will affect the cooling capacity of the heatsink, the resistor pack should be mounted above or to the side of the ASD — Never below the ASD. Maintain a minimum of six inches between the resistor pack and the ASD unit.

Heavy duty DBRs should be wired using the same gauge wire as the motor leads. Light duty DBRs may use one wire size smaller (AWG) than the motor leads.

The total wire length from the ASD to the DBR should not exceed ten feet.

The wiring from the ASD to the DBR should be twisted approximately two twists per foot throughout the length of the wire.

If EMI/RFI noise is of concern, the DBR wiring should be three-core screened cable. The screen should connect to the ASD enclosure and the resistor enclosure.

198 G7 ASD Operation Manual