3.17 Motor Application Precautions
118 YASKAWA SIEPC71061753C GA500 Technical Manual
■ Explosion-Proof Motors
You must test the motor and the drive together for explosion-proof certification. You must also test existing
installations of explosion-proof motors. The drive is not designed for explosion-proof areas. Install the drive in a
safe location.
The encoder used with pressure-resistant explosion-proof motors is intrinsically safe. When wiring between the
drive and encoder, always connect through a specialized pulse coupler.
■ Geared Motors
The continuous speed range is different for different lubricating methods and manufacturers. For oil lubrication,
continuous operation in the low-speed range can cause burnout. Contact the manufacturer for more information
about applications where operating at more than the rated frequency is necessary.
■ Single-Phase Motors
Variable speed drives are not designed to operate with single-phase motors. The drive is for use with three-phase
motors only. If you use capacitors to start the motor, it can cause a high frequency current to flow to the capacitors
and can damage the capacitors. A split-phase start or a repulsion start can burn out the starter coils because the
internal centrifugal switch is not activated.
■ Motors with Brakes
If you use a drive to operate a motor that has a brake connected to the output side, low voltage levels can cause
the brake to possibly not release at start. Use a motor with a brake that has a dedicated source of power for the
brake. Connect the brake power supply to the power supply side of the drive. Motors with built-in brakes make
noise when operating at low speeds.
◆ Notes on the Power Transmission Mechanism
For power transmission machinery that uses oil to lubricate gearboxes, transmissions, or reduction gears, make
sure that you use precaution if you operate the machinery continuously at low speed. Oil does not lubricate the
system as well at low speeds. If you operate at frequencies higher than the rated frequency, it can cause problems
with the power transmission mechanism. These problems include audible noise, decreased service life, and
decreased durability.
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