! E6581301!

A-18

1

High-speed operation at and above 50Hz/60Hz (rated frequency)

Operating at frequencies greater than 50Hz/60Hz will increase noise and vibration. There is also a possibility that
such operation will exceed the motor's mechanical strength under these con ditions and the bearing limits. You
should verify with the motor's manufacturer operating.

Method of lubricating load mechanisms

Operating an oil-lubricated reduction gear and gear motor in the low-spee d areas will worsen the lubricating effect.
Check with the manufacturer to find out about operable speed range.

Low loads and low inertia loads

The motor may demonstrate instability such as abnormal vibrations or overcur rent trips at light loads of 50% or
under of the rated load, or when the load's moment of inertia is extre mely small. If that happens reduce the carrier
frequency.

Occurrence of instability

Unstable phenomena may occur under the load and motor combinations sho wn below.
• Combined with a motor that exceeds applicable motor ratings recommended for the inverter
• Combined with special motors
To deal with the above lower the settings of inverter carrier frequency. (When performing vector control , set the
carrier frequency at 2kHz or more. If the carrier frequency is set belo w 2kHz, it will be automatically corrected to
2kHz by the inverter.)
• Combined with couplings between load devices and motors with high bac klash
In this case, set the S-pattern acceleration/deceleration function and ad just the response time inertial moment
setting during vector control or switch to V/f control (
RV
=
Q
).
• Combined with loads that have sharp fluctuations in rotation such as pi ston movements
In this case, adjust the response time inertial moment setting during vec tor control or switch to V/f control (
RV
=
Q
).
If it is operated in vector control mode (For torque control mode), only a motor whose capacity is same as inverter
standard or 1 size smaller should applied.

Braking a motor when power supply is lost

A motor with its power cut off goes into freewheel, and does not stop immediately. To stop the motor quickly as
soon as the power is cut off install an auxiliary brake. There are different kind s of brake devices, both electrical and
mechanical. Select the brake that is best for the system.

Loads that generate negative torque

When combined with loads that generate negative torque the protection for overvoltage and overcurrent on the
inverter will go into operation and may cause a trip. For this kind of si tuation, you must install a dynamic braking
resistor, etc. that complies with the load conditions.

Motor with brake

If a brake motor is used with the braking circuit connected to the outpu t terminals of the inverter, the brake cannot
be released because of a voltage drop at startup. Therefore, when using the i nverter along with a brake motor,
connect the braking circuit to the power supply side of the inverter, as shown i n the figure below. In most cases, the
use of a brake motor causes an increase in noise at low-speed.
!
B
IM
LOW
OUT1
! ! ! !
P24
Three-
phase
power
supply
MC
2
MC3
MC2
MC1
MC2
B
IM
MC3
MC1
MC3
FLB
FLC
ST
CC
Three-ph
ase
power
supply
LOW
(Non-exciting brake)
(Non-exciting brake)
MC1
MC2
Circuit configuration 1 Circuit configuration 2