Occurrence Of Instability (Abnormal Vibrations And Overcurrent Trips); Braking Motor When Turning Off Power Supply; Load That Produces Regenerative Torque; Motors With Brake - Toshiba TOSVERT VF-AS3 Instruction Manual

■ Occurrence of instability (abnormal vibrations and overcurrent trips)

Unstable phenomena such as abnormal vibrations and overcurrent trips may occur depending on
combinations of the inverter and motor, and load.
1) In the following cases, lower the settings of inverter carrier frequency.
• Combined with a motor that is extremely below applicable motor ratings for the inverter
• Combined with light load with a load factor of 50% or less
• Combined with load whose inertial moment is very small
• Combined with special motors
2
For details, refer to [6. 14].
2) In the following case, set the S-pattern acceleration/deceleration function (refer to [6.
27. 1]). When vector control is selected, adjust the load
[6. 23. 1] or switch to V/f constant mode (refer to [5. 2. 4]).
• Combined with couplings between load devices and motors with high backlash
3) When vector control is selected, adjust the load
1] or switch to V/f constant control (refer to [5. 2. 4]) in the following case.
• Combined with loads that have sharp fluctuations in rotation such as piston movements

■ Braking motor when turning off power supply

A motor with its power turn off goes into coasting state, and does not stop immediately.
To stop the motor quickly as soon as the power is turn off, install an auxiliary brake. There are differ-
ent kinds of brake devices, both electrical and mechanical. Select the brake that is best for the sys-
9
tem.

■ Load that produces regenerative torque

When combined with a load that produces regenerative torque, the overvoltage or overcurrent pro-
tection function may be activated to trip the inverter. Install a braking resistor to deal with it. For
details of the braking resistor, refer to [10. 3. 4].

■ Motors with brake

When motors with a brake are directly connected to the inverter's output, the brake cannot be
released at startup because of low voltage. Wire the brake circuit separately from the power circuit.
MC1
Power
supply
2. Installation and wiring
MC2
B
M
FLB FLC S2(ST)
MC3
MC1
MC3
MC3
MC2
Circuit diagram 1
moment of inertia
MC2
MC1
Power
supply
F CC
Run/Stop
Circuit diagram 2
2-54
E6582062
ratio (refer to
moment of inertia
ratio (refer to [6. 23.
Non-excitation
activation type brake
B
RY
R1A R1C
M
MC2