MITSUBISHI ELECTRIC INVERTER FR-F700 - Manual (Page 58)

59
Safety Precautions
To operate the inverter correctly and safely, be sure to
read the "instruction manual" before starting operation.
This product has not been designed or manufactured
for use with any equipment or system operated under
life-threatening conditions.
Please contact our sales office when you are
considering using this product in special applications
such as passenger mobile, medical, aerospace,
nuclear, power or undersea relay equipment or system.
Although this product is manufactured under strict
quality control, safety devices should be installed when
a serious accident or loss is expected by a failure of
this product.
The load used should be a three-phase induction motor only.
Operation
A magnetic contactor (MC) provided on the primary
side should not be used to make frequent starts and
stops. It could cause the inverter to fail.
However, at this time, the motor cannot be brought to a
sudden stop. Hence, provide a mechanical stopping/
holding mechanism for the machine/equipment which
requires an emergency stop.
It will take time for the capacitor to discharge after
shutoff of the inverter power supply. When accessing
the inverter for inspection, wait for at least 10 minutes
after the power supply has been switched off, and
check to make sure that there are no residual voltage
using a tester or the like.
Wiring
Application of power to the output terminals (U, V, W) of
the inverter will damage the inverter. Therefore, fully
check the wiring and sequence to ensure that wiring is
correct, etc. before powering on.
The terminals P/+, P1, N/- are provided for connection of a
dedicated option. Connect only a dedicated option. Do not
short the frequency setting power supply terminal 10 and
common terminal 5 or the terminal PC and terminal SD.
Do not wire the maker-dedicated terminal PR/PX.
Installation
Avoid hostile environment where oil mist, fluff, dust particles,
etc. are suspended in the air, and install the inverter in a clean
place or put it in an ingress-protected "enclosed" panel. When
placing the inverter in a panel, determine the cooling system
and panel dimensions so that the ambient temperature of the
inverter is within the permissble value. (refer to page 8 for the
specified value)
Do not install the inverter on wood or other combustible
material as it will be hot locally.
Install the inverter in the vertical orientation.
Setting
The inverter can be operated as fast as a maximum of
400Hz by parameter setting. Therefore, incorrect
setting can cause a danger. Set the upper limit using
the maximum frequency limit setting function.
A setting higher than the initial value of DC injection
brake operation voltage or operation time can cause
motor overheat (electronic thermal relay trip).
Inverter capacity selection
When operating a special motor or more than one motor in
parallel with a single inverter, select the inverter capacity so
that 1.1 times the total rated motor current is less than the
rated output current of the inverter.
Starting torque of the motor
The start and acceleration characteristics of the motor
driven by the inverter are restricted by the overload
current rating of that inverter. Generally the torque
characteristic is less than when the motor is started by
a commercial power supply. When torque boost
adjustment or simple magnetic flux vector cannot
provide enough starting torque, select the inverter of
one rank higher capacity or increase the capacities of
both the motor and inverter.
Acceleration and deceleration times
The acceleration/deceleration time of the motor depends
on the motor-generated torque, load torque and moment
of inertia of the load (GD
2 ).
When the current limit function or stall prevention function is
activated during acceleration/deceleration, increase the
acceleration/deceleration time as the actual time may
become longer.
To decrease the acceleration/deceleration time,
increase the torque boost value (setting of a too large
value may activate the stall prevention function at a
start, longer the acceleration time), use the simple
magnetic flux vector control, or increase the inverter
and motor capacities. To decrease the deceleration
time, it is necessary to add the brake unit (FR-BU, MT-
BU5), power regeneration common converter (FR-CV),
power regeneration unit (MT-RC) or a similar device to
absorb braking energy.
Power transfer mechanism
(gear, belt, chain, etc.)
When an oil-lubricated gear box, speed change gear or
similar device is used in the power transfer system,
note that continuous operation at low decelerated
speed only may deteriorate oil lubrication, causing
seizure. When performing fast operation at higher than
60Hz, fully note that such operation will cause strength
shortage due to the noise, life or centrifugal force of the
power transfer mechanism.
Instructions for overload operation
When performing operation of frequent start/stop of the
inverter, rise/fall in the temperature of the transistor
element of the inverter will repeat due to a continuous
flow of large current, shortening the life from thermal
fatigue. Since thermal fatigue is related to the amount
of current, the life can be increased by reducing bound
current, starting current, etc. Decreasing current may
increase the life. However, decreasing current will
result in insufficient torque and the inverter may not
start. Therefore, increase the inverter capacity to have
enough allowance for current.
Precautions for use of the inverter Precautions for selection
Precautions for Operation/Selection