VSD On/Off switching using an Intermediate Relay
In some instances, it might be required to switch a drive on/off by switching the power supply to the drive on/off (remote on/off power supply switch) – or required for a VSD to automatically start again after a power failure if it was switched on. Switching the power supply off while a drive is running a motor could however cause damage to the drive capacitors (cause instantaneous discharge shock impact on capacitors which will reduce the service life of the capacitors). It is therefore advised to rather install an Intermediate Relay to immediately instruct the VSD to Free Stop when a power failure occurs. This will also prevent the Err09 (Power Failure) fault occurring. Further to this, when switching the power supply immediately on again to start a motor could cause high current shocks if the motor did not yet stop completely (due to inertia), which could cause overcurrent failures. For these reasons one would rather use a Terminal Start/Stop method and also delay the start process. Doing this by switching the power source on and off can be accomplished by using an Intermediate Relay and setting the following Parameters:
- Install the Intermediate Relay as per the diagram below – only one set of Normally open Contacts is required (the diagram is for a drive with Single Phase 230V supply. If the input voltage is 3-Phase 380V, choose a 380V Intermediate Relay)
- Set b0-02 = 1 (Terminal Control)
- Set b1-07 = 1 (Free Stop Mode)
- Set b3-15 = 15.0 (DI1 On Delay time to delay the Start-up Process)
Intermediate Relay
Relay Connection
Using the above method will always use a Free Stop method. If this is not desired, the Intermediate Relay can also be connected to a different DI Terminal and COM with that DI Terminal function set = 43 (Free Stop) and also switching the DI logic (NO/NC) for that DI Terminal. Then a Normal Stop (Decelerate to Stop) method can be used for general Stop functions(b1-07=0) using the On/Off Switch and when there is a power failure the Intermediate Relay will ensure a Free Stop. Example: Connect Intermediate Relay to DI2 and COM and set b3-01=43 and then switch D12 logic by setting b3-25=00010.
Please Note: Using this method, when there is a power failure, the drive will go into Free Stop and switch off, and if the On/Off switch is still in an On state when the power returns, the drive will start automatically, but if it’s just a sudden power failure and the power returns very quickly before the drive switched off completely, the drive will not start automatically, the On/Off switch then first needs to be switched off and then on again (if it was still in an On state).
