3.6 Additional Connections
3.6.1 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).
•
Keep the output closed (voltage-free) as long as
the adjustable frequency drive is unable to
‘support’ the motor, e.g., 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
parameter 2-20 Release Brake Current
•
The brake engages when the output frequency is
less than the frequency set in
parameter 2-21 Activate Brake Speed [RPM]
or
parameter 2-22 Activate Brake Speed [Hz]
, only if
the adjustable frequency drive completes a stop
command.
If the adjustable frequency drive is in alarm mode or in an
overvoltage situation, the mechanical brake immediately
cuts in.
3.6.2 Parallel Connection of Motors
The adjustable frequency drive can control several motors
connected in parallel. The total current consumption of the
motors must not exceed the rated output current I
M,N
for
the adjustable frequency drive.
NOTICE!
Installations with cables connected in a common joint as
in
, is 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 adjustable
frequency drive cannot be used as motor protection for
the individual motor of systems with motors connected
in parallel. Provide further motor protection with
thermistors in each motor or individual thermal relays.
Circuit breakers are not suitable as protection.
LC filter
130BA170.10
Figure 3.32 Installations with Cables Connected in a
Common Joint
Problems are possible at start and at low RPM values if
motor sizes vary widely. The relatively high ohmic
resistance in the stator of small motors calls for a higher
voltage at start and at low RPM values.
Installation
Instruction Manual
38
Danfoss A/S © Rev. 2014-02-07 All rights reserved.
MG37A222
3
3
Summary of Contents for VLT AutomationDrive FC 302
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