Parker AC890PX Series, Product Manual

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Operating the Drive
6-18
AC890PX AC Drive
Application Advice

Application advice is available through our Technical Support Department, who can also arrange for on-site assistance
if required. Refer to the back cover of this manual for the address of your local Parker Hannifin Manufacturing
company.

Always use gold flash relays, or others designed for low current operation (5mA), on all control wiring.

Remove all power factor correction equipment from the motor side of the drive before use.

Avoid using motors with low efficiency and small cos ø (power factor) as they require a larger kVA rated drive to
produce the correct shaft kW.
Brake Motors
Brake motors are used in applications requiring a mechanical brake for safety or other operational reasons. The motor can be
a standard induction motor fitted with an electro-mechanical brake, or it could be a special conical rotor machine. In the case
of a conical rotor machine the spring-loaded brake is controlled by the motor terminal voltage as follows:
At rest the motor is braked.
When the motor is energised an axial component of the magnetic field due to the conical air-gap overcomes the force of the
brake spring and draws the rotor into the stator. This axial displacement releases the brake and allows the motor to accelerate
like a normal induction motor.
When the motor is de-energised the magnetic field collapses and the brake spring displaces the rotor, pushing the brake disc
against the braking surface.
Drives can be used to control the speed of conical rotor brake motors since the linear V/F characteristic maintains the motor
magnetic field constant over the speed range. It will be necessary to set the FIXED BOOST parameter to overcome motor
losses at low speed (see the FLUXING menu on the Keypad).
Using Output Contactors
The use of output contactors is permitted. It is recommended that this type of operation be limited to emergency use only or in
a system where the drive can be inhibited before closing or opening this contactor.