Additional Connections; Mechanical Brake Control; Parallel Connection Of Motors - Danfoss VLT HVAC Drive FC 102 Operating Instructions Manual

Electrical Installation

4.4 Additional Connections

4.4.1 Mechanical Brake Control

In hoisting/lowering applications, it is necessary to be
able to control an electro-mechanical brake:
•
Control the brake using any relay output or
digital output (terminal 27 or 29).
•
4 4
Keep the output closed (voltage-free) as long as
the frequency converter is unable to support the
motor, for example due to the load being too
heavy.
•
Select [32] Mechanical brake control in parameter
group 5-4* Relays for applications with an electro-
mechanical brake.
•
The brake is released when the motor current
exceeds the preset value in 2-20 Release Brake
Current.
•
The brake is engaged when the output frequency
is less than the frequency set in 2-21 Activate
Brake Speed [RPM] or 2-22 Activate Brake Speed
[Hz], and only if the frequency converter carries
out a stop command.
If the frequency converter is in alarm mode or in an over-
voltage situation, the mechanical brake immediately cuts
in.

4.4.2 Parallel Connection of Motors

The frequency converter can control several parallel-
connected motors. The total current consumption of the
motors must not exceed the rated output current I
the frequency converter.
NOTICE
Installations with cables connected in a common joint as
in Illustration 4.32 are only recommended for short cable
lengths.
NOTICE
When motors are connected in parallel, 1-29 Automatic
Motor Adaptation (AMA) cannot be used.
NOTICE
The electronic thermal relay (ETR) of the frequency
converter cannot be used as motor overload protection
for the individual motor in systems with parallel-
connected motors. Provide further motor overload
protection, for example thermistors in each motor or
individual thermal relays (circuit breakers are not
suitable as protection).
60
Operating Instructions
for
M,N
Illustration 4.32 Parallel Motor Connection
Problems may arise at start-up and at low RPM values if
motor sizes are widely different because small motors'
relatively high ohmic resistance in the stator calls for a
higher voltage at start-up and at low RPM values.
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MG11F502