External Stop/Start Setup for Multiple VSDs
In some instances, it might be required to Start and Stop multiple motors simultaneously (in some cases it might be required to have a fixed delay between start-ups of the various motors, in which case delay can be set on the DI terminals for the specific VSDs). In order to do that using an external On/Off switch, the VSDs needs to wired to each other with a single On/Off Switch as follows:
Since each VSD has its own 24V DC Supply on the digital inputs (Control Board), it’s important to remove the power from all secondary VSDs to ensure only one power source is used on the On/Off Switch. In order to do this, remove the bridge between the +24V and PLC terminals on all the secondary VSDs (please note that the power can only remove from drives from 4kW and larger).
Then also set the following parameter on each VSD:
- b0-02 = 1 (terminal control)
Note: If the External Switch has a Normally Closed connection (not Normally Open) the VSD Start/Stop function will operate in the opposite way intended. In this case, also set b3-25 = 00001(Low Level Valid).
Note: If it is required to delay the start of any of the specific motors (Cascade Control), for that motor VSD, set a Start delay on DI1 using b3-15 (DI1 ON delay time). If it is required to delay the stop of any of the specific motors, for that motor VSD, set a Stop delay on DI1 using b3-16 (DI1 OFF delay time).
If these VSDs also need to Stop simultaneously in the event of a Fault occurring on any one of the VSDs, each VSDs Relay output (with Fault Output trigger) also needs to be wired into the circuit as follows:
The also set the following Relay parameter on each VSD:
- b4-03 = 3 (Fault Output)
Please Note: For Smaller Drives with only one set of Relays (TA-TB-TC), use the TA2-TB2-TC2 Relay parameter settings.
Please see example of Large VSD Control Board with 2 sets of Relays below:
* Please Note: If the On/Off Switch is in the On state and a power failure occurs, the VSDs will automatically start again when the power returns (for such a scenario its best to rather make use of a Free Stop Mode for both VSDs and also allow for a Start Delay on the First VSD when the power returns). It is however not ideal to Start/Stop a VSD by switching the power supply On/Off – which is typically the case with regular power failures (causes instantaneous discharge shock impact on capacitors which will reduce the service life of the capacitors) – for a better method of achieving this using an Intermediate Relay, please see the following FAQ Entry: How to Setup an Intermediate Relay to Power a VSD On/Off. A better Stop/Start method for the first VSD would be to use separate Stop and Start Push Buttons as described below:
When using Push Buttons use a 3-Line Mode Stop/Start Setup:
- b0-02 = 1 (Terminal Control)
- b3-13 = 2 (3-Line Mode 1)
- b3-00 = 1 (RUN Enabled) -> DI1 Terminal Connection
- b3-02 = 3 (3-Line Control) -> DI3 Terminal Connection
- 3rd Line Connected to COM
If using FWD/REV as well with above, set:
- b3-13 = 3 (3-Line Mode 2)
- b3-01 = 2 (FWD/REV) -> DI2 Terminal Connection
