Unidrive M/HS Frame 5 to 6 Power Installation Guide 59
Issue Number: 9
Safety information Product information Mechanical installation
Electrical installation
Technical data UL listing information
If it is not practical to use an inverter-rated motor, an output choke (inductor) should be used. The
recommended type is a simple iron-cored component with a reactance of about 2 %. The exact value
is not critical. This operates in conjunction with the capacitance of the motor cable to increase the
rise-time of the motor terminal voltage and prevent excessive electrical stress.
4.9.4 Multiple motors
Open-loop only
If the drive is to control more than one motor, one of the fixed V/F modes should be selected
(Pr 05.014 = Fixed or Squared). Make the motor connections as shown in Figure 4-7 and Figure 4-8.
The maximum motor cable lengths specified in section 5.1.22 Maximum motor lengths and types on
page 98 apply to the sum of the total cable lengths from the drive to each motor.
It is recommended that each motor is connected through a protection relay since the drive cannot
protect each motor individually. For
connection, a sinusoidal filter or an output inductor must be
connected as shown in Figure 4-8, even when the cable lengths are less than the maximum permissible.
For high DC voltages or when supplied by a regen system, a sinusoidal filter is recommended. For
details of filter or inductor sizes refer to the supplier of the drive.
Figure 4-7 Preferred chain connection for multiple motors
Figure 4-8 Alternative connection for multiple motors
Motor protection
relay
Chain connection (preferred)
connection
Inductor
Motor protection
relay
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