Power Factor Correction; Light Load Conditions; Motor/Load Combinations; Motor Braking - Toshiba Q9 Installation And Operation Manual

Power Factor Correction

DO NOT connect a power factor correction capacitor or surge absorber to the output of the ASD.
If the ASD is used with a motor that is equipped with a capacitor for power factor correction, remove the
capacitor from the motor.
Connecting either of these devices to the output of the ASD may cause the ASD to malfunction and trip,
or the output device may cause an over-current condition resulting in damage to the device or the ASD.

Light Load Conditions

When a motor is operated under a continuous light load (i.e., at a load of less than 50% of its rated
capacity) or it drives a load which produces a very small amount of inertia, it may become unstable and
produce abnormal vibration or trips because of an over-current condition. In such a case, the carrier
frequency may be lowered to compensate for this undesirable condition (see Program  Special Controls

PWM Carrier
Note: When operating in the Vector Control mode the carrier frequency should be set to
2.2 kHz or above.

Motor/Load Combinations

When the ASD is used in combination with one of the following motors or loads, it may result in unstable
operation.
• A motor with a rated capacity that exceeds the motor capacity recommended for the ASD.
• An explosion-proof motor.
When using the ASD with an explosion-proof motor or other special motor types, lower the carrier
frequency to stabilize the operation. DO NOT set the carrier frequency below 2.2 kHz if operating the
system in the vector control mode.
Note: When operating in the Vector Control mode the carrier frequency should be set to
2.2 kHz or above.
If the motor being used is coupled to a load that has a large backlash or if coupled to a reciprocating load,
use one of the following procedures to stabilize motor operation.
• Adjust the S-Pattern acceleration/deceleration setting,
• If operating in the Vector control mode, adjust the response time, or
• Switch to the Constant Torque control mode.

Motor Braking

The motor may continue to rotate and coast to a stop after being shut off due to the inertia of the load. If an
immediate stop is required, a braking system should be used. For further information on braking systems
see DC Injection Braking Current on pg.
Q9 ASD Installation and Operation Manual
Frequency).
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