Communications Diagnostics Technical data
26
Commander S100 User Guide
4.5.5 Motor protection
The drive output (U, V, W) has fast-acting electronic short-circuit protection which limits the fault current to a maximum of 2.5 times the rated output
current and interrupts the current in approximately 5 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,
Motor Rated Current
(P0.06) must be set to suit the motor.
4.5.6 Motor winding voltage
The output voltage from a variable frequency drive 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.
Special precautions are recommended if the A.C. supply voltage exceeds 500 V when a motor cable length exceeding 10 m is used. If these
conditions apply it is recommended that an inverter-rated motor be used taking into account the voltage rating of the inverter.
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
Inverter-rated or inverter duty motors have a reinforced insulation system designed for the fast-rising pulsed output voltage (PWM) generated by
variable frequency drives.
4.5.7 /
Δ
motor operation
The voltage rating for and
Δ
connections of the motor should always be checked before attempting to run the motor.
The default setting of the motor rated voltage parameter is the same as the drive rated voltage, i.e.
400 V drive 400 V rated voltage
200 V drive 230 V rated voltage
A typical 3 phase motor would be connected in for 400 V operation or
Δ
for 230 V operation, however, variations on this are common e.g.
690 V
,
Δ
400 V.
Incorrect connection of the windings will lead to a very poor output torque or motor saturation and overheating.
Figure 4-5 Typical
/
Δ
connections in a motor
4.5.8 Output contactor
A contactor is sometimes required to be installed between the drive and motor for safety purposes. The recommended motor contactor is the AC3
type.
Switching of an output contactor should only occur when the output of the drive is disabled. Opening or closing of the contactor with the drive enabled
will lead to:
1.
Output Over Current
error (E003)
2. High levels of radio frequency noise emission (disturbance to nearby equipment)
3. Increased contactor wear and tear
Motor Rated Current
(P0.06) must be set correctly to avoid a risk of fire in the event of motor overload.
WARNING
NOTE
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 this circuit is interrupted with the motor running at high
current and low speed.
U
1
V
1
W
1
U
2
V
2
W
2
U
1
V
1
W
1
U
2
V
2
W
2
U
V
W
U
V
W
Star (Y)
Delta ( )
Δ
WARNING
Summary of Contents for COMMANDER S100
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