Simple Applications | International English |
5.8.5Start on the Fly
Normally if the inverter attempts to start a motor that is already rotating it will current limit, stall or slow the motor down. If Start on the Fly is selected it will sense the speed of the motor and ramp the motor from that speed back to the set point. This is useful if the motor is already turning for some reason, such as following a short input supply break.
Start on the fly can operate when the load is rotating in the reverse direction, for instance when a fan is rotating due to reverse pressure. In this case, the motor direction is tested at low torque in forward and reverse directions. This can have the undesirable effect that the motor rotates in both directions at start up.
5.8.6Electro-Mechanical Brake Control
The relays can be programmed to control a separate brake and a delay set (using appropriate parameters) so the motor can be energized prior to relay release. During the time set in the delay parameters, the inverter runs at its minimum frequency while the brake is energized, so that when the brake is released the motor will move immediately.
Output
Frequency
Minimum
Frequency
Time
Relay can be used to control external brake during these tmes
Figure
26 | MICROMASTER Applications Handbook |