Braking Resistors; Fuses; Rating Tables - ABB NBRA-6 Series Installation And Startup Manual

Braking Resistors

Fuses

Rating Tables

Installation and Start-up Guide for NBRA-6xx
Standard resistors are available for each ACS 600 / NBRA-6xx
combination. These resistors are specified in Table 2-1, and their
dimensions given in Appendix A. (Some combinations require the use
of two parallel-connected resistors.) Other resistors with a resistance
not below the minimum allowed resistance value (R) may also be used.
WARNING! Never use a braking resistor with a resistance value below
the minimum allowed resistance value specified for that particular
ACS 600 / braking chopper combination. The chopper and the
frequency converter are not able to handle the overcurrent caused by
the low resistance.
If the heat dissipation capacity (E
not sufficient for the application, it is possible to use a four resistor
assembly in which two standard resistors are connected in parallel and
two in series. This implementation does not change the total resistance
of the resistor assembly.
The NBRA-658, NBRA-659 and NBRA-669 require the use of braking
circuit fuses. Other units do not require the fuses if all of the following
provisions are fulfilled:
• the ACS 600 mains cable is protected with fuses
• the cable and the fuses are of the type specified for that particular
converter model in its Installation and Start-up Manual
• the braking chopper circuit cables are as specified in this Guide.
The fuses in the braking circuit protect the chopper and the braking
circuit cables in a cable short-circuit situation. The fuses do not protect
the cables, the chopper or the resistor against overload. Overload
protection can be implemented by wiring the temperature sensor of the
resistor to the Enable Input of the chopper and simultaneously
connecting the Relay Output of the chopper to the main contactor
control circuit of the ACS 600.
The fuses must be installed as near as possible to the ACS 600
intermediate circuit terminals (UDC+ and UDC–). Unprotected cable
length must not exceed 0.5 metres.
The standard braking choppers, braking resistors, cables and fuses are
specified in Tables 2-1 and 2-2. (See also Chapter 4 – Electrical
Installation.)
The Maximum Braking Power of the ACS 600 / NBRA-6xx combination
is given for a reference braking cycle (the drive brakes for one minute
every ten minutes). If the actual cycle does not correspond to the
reference cycle, the maximum allowed braking power must be
calculated. See Appendix B – Maximum Braking Power for
instructions.
Chapter 2 – Overview
) of the standard braking resistor is
R
2-3