Mechanical brake control
For hoisting applications, it is necessary to be able to
control an electro-magnetic brake.
For controlling the brake, a relay output (01 or 04) is
required. This output must be kept closed (voltage-
free) during the time when the adjustable frequency
drive is not able to 'hold' the motor, due to a load that
is too large, for example. In parameter 323 or 326 (re-
lay outputs 01, 04), select Mechanical brake control
[32] or Extended mechanical brake control [34] for ap-
plications with an electro-magnetic brake.
During start/stop and ramp-down, the output current is
monitored. If Mechanical brake control [32] is selected
and the current is below the level selected in parame-
ter 223 Warning: Low current, the mechanical brake is
closed (voltage-free).
As a point of departure, a current can be selected
which is approx. 70% of the magnetizing current. Pa-
rameter 225 Warning: Low frequency states the fre-
quency during ramp-down at which the mechanical
brake is to close again.
If Extended mechanical brake control [34] is selected
the mechanical brake is closed (voltage-free) during
start until the output current is above the level selected
in parameter 223 Warning: Low Current.
During stop mechanical brake is released until the fre-
quency is below the level selected in parameter 225
Warning: Low frequency.
Notice by Extended mechanical brake control [34] that
the brake does not close if the output current falls un-
der parameter 223 Warning: Low current.
Nor does a current low level warning appear.
In extended mechanical brake mode, an overcurrent
trip (alarm 13) can be reset by an external reset.
If the adjustable frequency drive is brought into an
alarm condition or an overcurrent or overvoltage sit-
uation, the mechanical brake will immediately cut in.
NOTE
The application shown is only for hoisting
without counterweight.
Control of mechanical brake:
Parameter: Setting: Data value:
323 Relay 01 or par. 326 relay 04 Mechanical brake control [32]
323 Relay 01 or par. 326 relay 04 Extended mechanical brake control [34]
223 Warning: Low current
approx. 70% of magnetizing current
1)
225 Warning: Low frequency
3-5 Hz
2)
122 Function at stop Pre-magnetization [3]
120 Start delay time 0.1-0.3 sec
121 Start function
Start frequency/voltage clockwise
3)
[3]
130 Start frequency Set to slip frequency
131 Initial voltage
The voltage must correspond to the frequency that has been set in pa-
rameter 130.
1. During start and stop, the current limit in pa-
rameter 223 determines the switching level.
2. This value indicates the frequency during
ramp-down at which the mechanical brake is
to be closed again. This assumes that a stop
signal has been given.
3. It must be ensured that the motor starts clock-
wise (hoist), since otherwise the adjustable
frequency drive may drop the load. Switch U,
V, W connections, if required.
VLT
®
5000 Series
198 MG.51.C5.22 - VLT
p
is a registered Danfoss trademark.
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