Earth Connection; Control Of Mechanical Brake - Danfoss VLT FCD 311 Design Manual

Earth connection

As leak current to the earth is higher than 3.5 mA,
the frequency converter must always be earthed ac-
cording to prevailing national and local regulations.
To guarantee that the earth cable has a good me-
chanical connection to PE-termina, the cable cross
section must be at least 10 mm
wires that are terminated separately . To increase
safety you can install an RCD (Residual Current De-
vice), which guarantees that the frequency converter
trips when leak current becomes too high. See also
RCD Application Note MN.90.GX.02.

Control of mechanical brake

No. 122* 123*
MBR- MBR+
* (optional)
In lifting/lowering applications you need to be able to
control an electromagnetic brake. The brake is con-
trolled using the special mechanical brake control/
supply terminals, a relay output or digital output (ter-
minal 46). See Connection of mechanical brake for
further details.
The output must be kept voltage-free for the period
of time during which the frequency converter is not
able to 'support' the motor, for example due to the
load being too great. If not using the special me-
chanical brake control/supply terminals (122-123),
select Mechanical brake control in parameter 323 or
341 for applications with an electromagnetic brake.
When the output frequency exceeds the brake cut
out value set in par. 138, the brake is released if the
motor current exceeds the preset value in parameter
140. When stopping the brake is engaged when the
output frequency is less than the brake engaging fre-
quency, which is set in par. 139.
If the frequency converter is placed at alarm status
or in an overvoltage situation the mechanical brake
is cut in immediately .
NB!:
This application is only
for lifting/lowering without a counterbalance.
MG.04.A1.02 - VLT is a registered Danfoss trade mark
2
or 2 rated earth
Mechanical brake
(UDC=0.45 X
Mains Voltage)
®
VLT FCD Series
41