Delay VSD Restart after Low Current Protection
When setting up a VSD for Low Current Protection (typically for Dry Run Protection for Water Pumps) a low Current Alarm (Err15) will be triggered when the specific condition occurs (please see detailed FAQ entry HERE).
In some cases, however it is required to set the VSD to automatically restart again after a delay period. This requires that the VSD is set up to clear the Error to allow the Auto Restart. This can be done as follows:
Connect terminals DI1 and Common and then set:
- b0-02 = 1 (terminal control)
- bb-09 = 20 (unlimited fault auto reset times)
- bb-11 = 100s (time interval of reset times)
- b1-07 = 1 (free stop mode)
- b3-15 = 3000s (DI1 On Delay time to delay the Start-up Process)
Using the above settings will clear the Error after 100 seconds (longest delay possible for clearing the Error) and then allow the VSD to start again after 3000 seconds (longest delay possible for the DI terminal).
The issue with the 3000 second delay on the DI terminal however is that the delay will always be applicable, so the VSD will always only start after 3000 seconds after switching it on. Further to this, in many cases a max of 3000 seconds delay is too short. Another shortcoming is that this method clears all faults, and not just the Low Current Error.
Another way to implement such a delay (instead of delaying the DI terminal) would be to use an external timer which gets triggered by the VSD Low Current Error (and thus ignores all other errors). Once the timer is triggered by the VSD to start, the timer will, after a set delay period, send a signal to the VSD to clear the error (this will clear all errors, but the timer is only triggered to start based on the Low Current Error occurring).
The following example explains how to do this using a Velleman VM206 Universal timer module (with USB interface). Please see the Velleman page for more information HERE (manual and software can be downloaded from this page as well).
Programming the Velleman VM206 Timer
Firstly, install the Velleman VM206 Software to a PC and then connect the Velleman VM206 to the PC using the supplied USB cable. Once connection between the PC and Timer has been established, the timer settings can be specified and sent to the timer using the “Send” command. For the purpose of this specific example, the Timer Mode = 10 should be used with two Time Sequences as follows (please see image that follows as example):
- t1: Relay = Off; Time = Set time depending on how long the timer should wait before sending a signal to clear the VSD error state (10 seconds in this example).
- t2: Relay= On; Time = Set time for how long the timer should send the signal to clear the VSD error state (1 second in this example).
- Do not select any of the Tick boxes for the 3 options at the bottom
Wiring the Velleman VM206 Timer and VSD
To provide power to the timer, connect the VSD 10+V terminal with the Timer + terminal and the VSD GND terminal with the Timer – terminal.
To receive the trigger from the VSD when the Low Current Protection Error occurs, connect the VSD Relay terminal TA with the Timer IN1 terminal and the VSD relay terminal TC with the Timer GND terminal.
To send the trigger from the Timer after the set delay time to clear the error on the VSD, connect the VSD terminal DI3 with the Timer COM terminal and the VSD COM terminal with the Timer NO terminal.
VSD Wiring and Parameter Settings
Set the VSD for Low Current Protection (typically for Dry Run Protection for Water Pumps) a low Current Alarm (Err15) will be triggered when the specific condition occurs (please see detailed FAQ entre HERE).
Set the VSD Relay Output to start the Timer once the Low Current Error occurs as follows:
- b4-03 = 26 (Zero Current State) – this will switch the relay once the Low Current Error Occur.
- b4-15 = 1 (Relay 2 Off Delay Time) – this is a slight delay on the switch to prevent conflict with the Dry Run Protection Settings which causes the Relay to immediately switch back again.
Please Note: For Smaller Drives with only one set of Relays (TA-TB-TC), use the TA2-TB2-TC2 Relay parameter settings.
Set the VSD Digital Input to clear its error state once it receives a trigger from the Timer as follows:
- b3-02 = 37 (Fault Reset) – this will clear the VSD error state.
Then, since the VSD needs to auto start after resetting the error via the timer, the VSD needs to be set up to auto start. To do this, connect DI1 and COM (ideally add a manual switch between DI1 and COM to force switch the VSD off). Set b0-02 = 1 (Terminal Control). This will ensure that as long as the VSD is not in an error state it will run (if a manual switch is connected between DI1 and COM the switch needs to be on).
Wiring Diagram
For scenarios where this setup might be applicable, please see:
– To set up a EMHEATER VSD with a Pressure Transmitter to provide Constant Water Pressure using the VSD Parameters to set a Fixed Target Pressure, please see the relevant FAQ entry HERE.
– To set up a EMHEATER VSD with a Pressure Transmitter to provide Constant Water Pressure using an external analog signal (such as a PLC) to modify the target pressure (Variable Target Pressure), please see the relevant FAQ entry HERE.
– To set up a EMHEATER VSD with a Pressure Transmitter to provide Constant Water Pressure using an external Multi-Stage Switch to modify the target pressure (Target Pressure Selector), please see the relevant FAQ entry HERE.
– To set up a EMHEATER VSD with a Pressure Transmitter for Frequency Control using a PID (Manage Water Outflow), please see the relevant FAQ entry HERE.
– To set up a EMHEATER VSD with a Pressure Transmitter for Frequency Control using a PID (Manage Water Inflow), please see the relevant FAQ entry HERE.
– To set up a EMHEATER VSD with AI Input Overrun Limit (using a Pressure Transmitter as STOP), please see the relevant FAQ entry HERE.
For additional Protection Features, please also see:
– To set up a EMHEATER VSD End of Curve Parameters (PID Signal Loss Protection), please see the relevant FAQ entry HERE.
– To set up a EMHEATER VSD Low Current Protection (Dry Run Protection), please see the relevant FAQ entry HERE.
