Mitsubishi Electric FR-E700EX Manual page 44

Precautions for the use of a sensorless
PM motor
SAFETY INSTRUCTIONS
 Do not use a sensorless PM motor for an application where the
motor is driven by the load and runs at a speed higher than the
maximum motor speed.
Cautions for model selection
 Select a sensorless PM motor which has the rated torque equal to or
higher than the continuous effective torque.
 When unbalanced torque is generated, such as in a vertical lift
machine, it is recommended that the unbalanced torque of the
machine be kept under 70% of the sensorless PM motor rated
torque.
 Create the operating pattern by considering the settling time.
 The load to motor inertia ratio must be equal to or below the
recommended ratio. If the ratio is too large, the expected
performance may not be achieved.
Combination of motor and drive
unit
 Use the same sensorless PM motor capacity as the drive unit
capacity.
 Only one sensorless PM motor can be connected to a drive unit.
 A sensorless PM motor cannot be driven by the commercial power
supply.
 Do not use a synchronized or induction-synchronized motor, that is
not a sensorless PM motor.
Installation
 While power is ON or for some time after power-OFF, do not touch
the motor since the motor will be extremely hot. Touching these
devices may cause a burn.
 Do not drop or apply a strong impact on the motor as they are
precision devices. They may be damaged from such stress or
shock.
 Do not get on or place heavy objects on the motor. Doing so may
result in an injury or damage.
 The system must withstand high speeds and high acceleration/
deceleration.
 Ensure the machine rigidity, and keep the machine resonance point
at a high level.
 Mount the motor on a nonflammable material. Mounting them
directly on or near flammable material may result in fires.
 Securely fix the motor onto the machine. Insufficient fixing may
cause the motor to be dislocated during operation.
 Install electrical and mechanical stoppers at the stroke end.
 Do not hammer the shaft of the motor and the rotor of the motor
when installing a pulley or a coupling. Doing so will cause a failure.
For the motor with a key shaft, fit the pulley or a coupling into a place
using the screw hole at the shaft end. Use a pulley extractor when
removing the pulley.
 When installing the motor with its shaft facing upward, take
measures on the machine side to prevent oils from infiltrating into
the motor from the gear box, etc.
Wiring
 Applying the commercial power supply to input terminals (U, V, W) of
a sensorless PM motor will burn the sensorless PM motor. The
sensorless PM motor must be connected with the output terminals
(U, V, W) of the drive unit.
 The sensorless PM motor is a synchronous motor with embedded
magnets. High-voltage is generated at motor terminals while the
motor is running even after the drive unit power is turned OFF.
Before wiring or inspection, confirm that the motor is stopped.
For applications where the motor is driven by the load, the low-
voltage manual contactor, which is installed at the drive unit's output
side, must be opened before wiring or inspection. Otherwise an
electric shock may occur.
The drive unit power must be turned ON before closing the contacts
of the contactor at the output side. Do not use a magnetic contactor
at the drive unit's output side.
 Match the input terminals (U, V, W) of the motor and the output
terminals (U, V, W) of the drive unit when connecting.
 When the sensorless PM motor is connected, the wiring length must
be 30m or shorter.
 Securely earth (ground) the unit to prevent electric shocks and to
stabilize the electric potential in the control circuit.
 Connect the earthing (grounding) wire to the protective earth (PE)
terminal via the drive unit protective earth (PE) terminal for the motor
earthing (grounding).
 Faults such as a position mismatch may occur if the earthing
(grounding) is insufficient.
 Check the wiring and sequence programs thoroughly before
switching the power ON.
 Carefully select the cable clamping method, and make sure that
bending stress and the stress of the cable's own weight are not
applied on the cable connection section.
 In an application where the motor moves, determine the cable
bending radius according to the cable bending life and wire type.
Operation
 It takes approx. 0.1s (magnetic pole detection time) to start a motor
after a start signal is input.
 The sensorless PM motor is a synchronous motor with embedded
magnets. If an instantaneous power failure occurs to cause the
motor to coast, induced voltage is generated.
The drive unit's DC bus voltage rises if the motor coasts fast in this
condition. When using the automatic restart after instantaneous
power failure function, it is recommended to also use the
regenerative avoidance operation to make startups stable.
 Do not use a product which is damaged or has parts missing. In that
case, replace the product.
 Do not apply a load exceeding the tolerable load onto the motor
rotor. The shaft or the rotor may break.
 Torque may drop due to temperature increase of the motor. Be sure
to use the motor within the specified ambient temperature.
Others
 Do not touch the motor with wet hands.
 Do not modify the motor.
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