Nidec 09201760D Installation Manual Download

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Electrical Installation

Unidrive M Modular Installation Guide

Issue Number: 2

Ground connections

The drive must be connected to the system ground of the AC supply.
The ground wiring must conform to local regulations and codes of
practice.

6.6.1 Main AC supply contactor

The recommended AC supply contactor type is AC1.

6.7 Output circuit and motor protection

The output circuit has fast-acting electronic short-circuit protection which
limits the fault current to typically no more than five times the rated
output current, and interrupts the current in approximately 20 µs. No
additional short-circuit protection devices are required.
The drive provides overload protection for the motor and its cable. For
this to be effective, Pr

00.046

Motor rated current

must be set to suit the

motor.

There is also provision for the use of a motor thermistor to prevent over-
heating of the motor, e.g. due to loss of cooling.

6.7.1 Cable types and lengths

Since capacitance in the motor cable causes loading on the output of the
drive, ensure the cable length does not exceed the values given in Table
6-13 to Table 6-16.
Use 105

C (221

F) (UL 60/75

C temp rise) PVC-insulated cable with

copper conductors having a suitable voltage rating, for the following
power connections:
•

AC supply to external EMC filter (when used)

•

AC supply (or external EMC filter) to drive

•

Drive to motor

•

Drive to braking resistor

Table 6-13 Maximum motor cable lengths (200 V drives)

Table 6-14 Maximum motor cable lengths (400 V drives)

Table 6-15 Maximum motor cable lengths (575 V drives)

Table 6-16 Maximum motor cable lengths (690 V drives)

•

Cable lengths in excess of the specified values may be used only
when special techniques are adopted; refer to the supplier of the
drive.

•

The default switching frequency is 3 kHz for open-loop and closed-
loop vector and 6 kHz for servo.

High-capacitance cables

The maximum cable length is reduced from that shown in Table 6-13 to
Table 6-16 if high capacitance motor cables are used.
Most cables have an insulating jacket between the cores and the armor
or shield; these cables have a low capacitance and are recommended.
Cables that do not have an insulating jacket tend to have high
capacitance; if a cable of this type is used, the maximum cable length is
half that quoted in the tables. (Figure 6-9 shows how to identify the two
types.)

Figure 6-9 Cable construction influencing the capacitance

The cable used for Table 6-13 to Table 6-16 is shielded and contains four
cores. Typical capacitance for this type of cable is 130 pF/m (i.e. from
one core to all others and the shield connected together).

6.7.2 Motor winding voltage

The PWM output voltage can adversely affect the inter-turn insulation in
the motor. This is because of the high rate of change of voltage, in
conjunction with the impedance of the motor cable and the distributed
nature of the motor winding.
For normal operation with AC supplies up to 500 Vac and a standard
motor with a good quality insulation system, there is no need for any
special precautions. In case of doubt the motor supplier should be
consulted.

Electrochemical corrosion of earthing terminals

Ensure that grounding terminals are protected against
corrosion i.e. as could be caused by condensation.

00.046

Motor rated current must be set correctly to avoid

a risk of fire in the event of motor overload.

200 V Nominal AC supply voltage

Model

Maximum permissible motor cable length for each of

the following switching frequencies

kHz