Braking Resistors - Siemens SIMOVERT MASTERDRIVES Betriebsanleitung

10.2004
4

Braking Resistors

WARNINGS
WARNINGS
Siemens AG 6SE7087-6CX87-2DA1
SIMOVERT MASTERDRIVES
The braking resistors listed in chapter 7 "Technical Data" match the
braking units and allow full utilization of the braking capability.
When braking resistors and braking units are combined, it must be
guaranteed that the resistance of a resistor is not less than the
minimum allowed resistance, otherwise the braking unit may be
destroyed!
Higher values of the resistors are allowed. The higher the resistance
value, however, the lower the braking power. The braking power varies
indirectly in proportion to the resistance value (double the resistance
value → half the braking power).
During operation the surface of the braking resistors may have
temperatures of several hundred degrees C. Therefore cooling air must
not contain flammable or explosive items or gases.
If a resistor is wall-mounted, the wall must not be flammable.
The external braking resistor must be mounted separately and
connected to the plant supply.
The braking resistors recommended by Siemens have a thermocontact
(NC contact) which trips when the resistor overloads. In this event, the
converter must be disconnected from the supply via a main contactor.
The correct functioning of the thermal contact must be checked by the
plant manufacturer upon commissioning!
If the main contactor is controlled via the appropriate output of the
converter or inverter (X9), the thermocontact can be connected to a
binary input that is parameterized as a fault input (see Fig. 3-8).
Braking Unit
Braking Resistors
4-1