Control Techniques Commander SE Series User Manual page 27

The ground loop impedance must conform to the requirements of local safety
regulations. The ground connections must be inspected and tested at
appropriate intervals.
WARNING
Earth and ground leakage
The Drive has a very small leakage current between the power lines and ground, which
is of no consequence.
The RFI filter has a higher leakage current, data is given in section 4.5.4, Tables 4.11
to 4.14. When the standard and low cost filters are used, a permanent fixed ground
connection must be provided which does not pass through a connector or flexible
power cord.
Motor cables
For routine EMC precautions
Use either of the following:
• Cables containing three power conductors plus a ground conductor
• Three separate power conductors plus a ground conductor
For full EMC precautions, where required (see section 4.5.2)
Use shielded (screened) or steel-wire armoured cable having three power conductors
plus a ground conductor.
If the cable between the Drive and the motor is to be interrupted by a
contactor or circuit breaker, ensure that the Drive is disabled before the
contactor or circuit breaker is opened or closed. Severe arcing may occur if
WARNING
this circuit is interrupted with the motor running at high current and low
speed.
Maximum motor cable lengths
The capacitive loading of the Drive by the motor cable means that the cable length
limits shown in Table 4.1 must be observed. Failure to do so can result in spurious
OI.AC tripping of the Drive. If longer cable lengths are required, consult your local
Drive Centre or Distributor.
Table 4.1 Maximum motor cable lengths
Drive Size
1
2
3
4
High Capacitance Cables
Most cables have an insulating jacket between the cores and the armour 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 high capacitance cable is used, the maximum cable lengths in Table 4.1 should be
halved.
For further information please refer to the Commander SE Advanced User Guide.
Multiple Motors
For advice on multiple motor applications where a number of small motors are
connected to the output of one Drive, please refer to the Commander SE Advanced
User Guide.
Commander SE User Guide
Issue Number 5
Maximum motor cable length
Meters Feet
75 246
100 330
100 330
100 330
23