ABB NBRA-653C Braking chopper

ABB NBRA-653C Braking chopper

Description

The NBRA-6xx Braking Choppers are optional devices for ACS 600 Family frequency converters.

The chopper connects the braking resistor to the intermediate circuit of the frequency converter whenever the voltage in the intermediate circuit exceeds the maximum limit. 

The maximum limit is equal to 1.21 · 1.35 · U1max. U1max is dependent on the chopper voltage selection (see Chapter 3 – Voltage Selection and Mechanical Installation). With the selection 400V, U1max is 415 V; with the selection 500V, U1max is 500 V; with the selection >500V (NBRA-66x), U1max is 690V. Energy consumption by resistor losses lowers the voltage until the resistor can be disconnected. This limit is equal to 1.19 · 1.35 · U1max. The energy generated by the motor during a fast deceleration of the drive typically causes the voltage to rise in the intermediate circuit.

Note: Drive Parameter 20.5 (20.7 for ACP 600) OVERVOLTAGE CTRL must be set to OFF to enable chopper operation.

The chopper control board supervises system status and detects failures such as:

• braking resistor and resistor cable short circuits

• chopper (IGBT) short circuit

• chopper control board failure

Technical Specifications