Danfoss VLT HVAC Drive FC 102 Design Manual page 186

Electrical Installation Con...
Motor
U
2
U
1
FC
96
Motor
U
2
U
1
FC
96
10 10
Illustration 10.18 Changing Motor Rotation
Requirements for enclosures F1/F3
Each inverter module must have the same number of
motor phase cables and they must be in quantities of 2
(for example, 2, 4, 6, or 8). 1 cable is not allowed. The
cables are required to be equal length or within 10%
between the inverter module terminals and the first
common point of a phase. The recommended common
point is the motor terminals. For example, if inverter
module A used a 100 m (328 ft) cable, then subsequent
inverter modules could use a cable between 90–110 m
(295–360 ft) in length.
Requirements for enclosures F2/F4
Each inverter module must have the same number of
motor phase cables and they must be in quantities of 3
(for example, 3, 6, 9, or 12). 1 or 2 cables are not allowed.
The cables are required to be equal length or within 10%
between the inverter module terminals and the first
common point of a phase. The recommended common
point is the motor terminals. For example, if inverter
module A used a 100 m (328 ft) cable, then subsequent
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2 2
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1 1
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V W
2 2
V W
1 1
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Danfoss A/S © 11/2017 All rights reserved.
®
VLT HVAC Drive FC 102
inverter modules could use a cable between 90–110 m
(295–360 ft) in length.
10.7.1 Motor Thermal Protection
The electronic thermal relay in the drive has received UL
Approval for single motor overload protection, when
parameter 1-90 Motor Thermal Protection is set for ETR Trip
and parameter 1-24 Motor Current is set to the rated motor
current (see the motor nameplate).
For motor thermal protection, it is also possible to use the
®
VLT PTC Thermistor Card MCB 112 option. This card
provides ATEX certification to protect motors in explosion
hazardous areas Zone 1/21 and Zone 2/22. When
parameter 1-90 Motor Thermal Protection, set to [20] ATEX
ETR, is combined with the use of MCB 112, it is possible to
control an Ex-e motor in explosion hazardous areas.
Consult the programming guide for details on how to set
up the drive for safe operation of Ex-e motors.
10.7.2 Parallel Connection of Motors
The drive can control several parallel-connected motors.
For different configurations of parallel-connected motors,
see Illustration 10.19.
When using parallel motor connection, observe the
following points:
•
•
•
•
•
•
Run applications with parallel motors in U/F
mode (volts per hertz).
+
VVC mode can be used in some applications.
Total current consumption of motors must not
exceed the rated output current I
Problems can occur at start and at low RPM if
motor sizes are widely different because the
relatively high ohmic resistance in the stator of a
small motor demands a higher voltage at start
and at low RPM.
The electronic thermal relay (ETR) of the drive
cannot be used as motor overload protection.
Provide further motor overload protection by
including thermistors in each motor winding or
individual thermal relays.
When motors are connected in parallel,
parameter 1-02 Flux Motor Feedback Source cannot
be used, and parameter 1-01 Motor Control
Principle must be set to [0] U/f.
for the drive.
INV
MG16C302