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Menu 12

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Performance RFC mode

230 Unidrive SP Advanced User Guide

www.controltechniques.com Issue Number: 10

If the current magnitude falls below the lower current threshold the brake is applied immediately. The lower threshold should be set to the required

level to detect the condition where the motor has been disconnected from the drive. If this parameter is set to zero the loss of current will not cause

the brake to be applied. However, the flux detection and current threshold latch will be reset when the drive is disabled.

When stopping, the drive reference can be removed (i.e. Pr 1.11 = 0), but the brake will remain energized (open) until the motor has remained at a

speed below the brake apply speed for the delay defined by Pr 12.46. The delay prevents rapid activation and de-activation of the brake when fine

control of a motor is required close to zero speed.

See Pr 12.45.

The post-brake release time is used to allow for the brake release time. From the time that the drive is enabled and then during this period the speed

reference is held constant at zero, so that there is no sudden increase in motor speed when the brake actually releases.

The brake apply delay is used to allow for the brake application time. During this period the Hold zero speed parameter (Pr 6.08) is one, and so the

drive is enabled with zero speed reference. This ensures that the motor remains stationary while the brake is being applied.

12.43

Low current threshold

Drive modes Open-loop, Closed-loop vector, Servo