Chapter 3 Environment description and installation
3-13
(a) Correct (b) Incorrect
(c) Incorrect
To ensure maximum safety, use correct wire size for the main power circuit and control circuit
according to the required wiring regulations.
On completion, check that the wiring is correct and terminal screws are secured.
3.3.5 Long motor cables: effects of volt drop and capacitance
When the cable between the
iDrive
and the motor is too long, the effect of volt drop along the cable
and cable capacitance must be considered. For very long cables it is sometimes necessary to use
iDrive
one frame size higher than motor power rating.
Phase-to-phase voltage drop (V
d
)
V
d
= 3 × resistance of wire (
Ω
/km) × length of line (mts) × current × 10
-3
To prevent RF problems and excessive high frequency ground leakage currents the
iDrive
carrier
frequency (function
b86
) should be adjusted based on the length of the motor cable, for example:
Motor cable length
< 25m
< 50m
< 100m
> 100m
Carrier frequency (b86) < 16kHz
< 12kHz
< 8kHz
< 5kHz
3.3.6 Input side AC reactor
An AC input reactor can be installed to reduce the harmonic content of the
iDrive
input current. If
the harmonic distortion is reduced, the RMS input current is also reduced.
An AC reactor can also be installed on the output side of
iDrive
when the motor cable is excessively
long and can counter the effect of cable capacitance and nuisance tripping. Contact IMO for details.
Input reactor specifications
Line input side AC inductance (typical)
iDrive
model
Current (A)
Inductance (mH)
040-21-# 5.0
2.1
075-21-# 5.0
2.1
150-21-# 19.0
1.1
220-21-# 25.0
0.71
075-43-#
2.5 8.4
150-43-# 5.0
4.2
EDX -
220-43-# 7.5
3.6
