Lenze 520 series Technische Beschreibung Seite 56

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5.4.3 OVERCURRENT RELEASE
To protect the brake resistors from overboad, a thermat overcurrent release must be
provided.
The following conditions may damage the brake resistor and the brake chopper, if
used without overcurrent release:
Mains overvoltages, which
-
Overboad of the brake resistor
-
Overload
of the brake chopper
-
This must be avoided by:
keeping the minimum resistance (RBRmin)
-
using resistors with integrated or external overload surveillance e.g. bimetal
-
relays, which disconnects the controller(s) from the mains
Release current
Overcurrent release for stationary generator mode on request.
increase the DC bus voltage
1/Rated power of the brake resistor
=~/
Brake resistor
4Q DC Chopper 520 series
-
Cont. brake current
=
Lenze