Operation Above 60 Hz; Power Factor Correction; Light Load Conditions; Motor/Load Combinations - Toshiba G7 Operation Manual

Operation Above 60 Hz

A motor produces more noise and vibration when it is operated at frequencies above 60 Hz. Also, when
operating a motor above 60 Hz, the rated limit of the motor or its bearings may be exceeded; this may void
the motor warranty.
Contact the motor manufacturer for additional information before operating the motor above 60 Hz.

Power Factor Correction

DO NOT connect a power factor correction capacitor or surge absorber to the output of the drive.
If the drive 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 drive may cause the drive to malfunction and trip,
or the output device may cause an over-current condition resulting in damage to the device or the drive.

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 condition (see Program ⇒ Special Control Parameters
⇒
Carrier Frequency).

Motor/Load Combinations

When the drive 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 drive.
• An explosion-proof motor.
When using the drive 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.
• If the motor that is coupled to a load has a large backlash or a reciprocating load, use one of the
following procedures to stabilize its operation.
• Adjust the S-pattern acceleration/deceleration setting,
• If in the Vector control mode, adjust the response time, or
• Switch to the Constant Torque control mode.

Load-produced Negative Torque

When the drive is combined with a load that produces negative torque, the over-voltage or over-current
protective function of the drive may cause the drive to trip.
To minimize the effects of negative torque a dynamic braking system may be used. The dynamic braking
system uses a braking resistor that must be suitably matched to the load.
G7 ASD Operation Manual 19