VSD Frequency (motor speed – Hz) can be controlled using an external device (PID) such as a Pressure/Level Transmitter. For parameter settings, please consider the following example:
Example/Requirements as follows:
- PID: A 2-wire Level Transmitter is used requiring a 24VDC supply and with 0-5m measurement range, providing a 4-20mA output (analog output).
- Connection: Connect the PID red cable to the VSD +24V terminal; Connect the green cable to the VSD AI2 terminal; Connect the VSD COM and GND terminals to each other. Please use shielded cable to prevent electromagnetic interference by other appliances on the analog signal sent to the VSD. For EMC Mitigation: 1) Allow for at least 20cm distance between communication cables and motor wires. 2) Do not use the same cable tray. 3) Insert wires in metal pipes if possible.
- Frequency Requirement: For this scenario the requirement is to put a level transmitter in a large dam/tank in order to measure how full/empty the dam/tank is. The requirement is then for the VSD to run a motor (pump) which pumps water from the dam/tank at full speed when the dam/tank is full (Level Transmitter will measure 5m), and to gradually reduce the speed of the motor as the dam/tank level drops in order to maintain a dam/tank level of 1m (below this level the VSD must switch off).
VSD Parameters to be set as follows:
- b0-02 = 1 (set Command Source selection = Terminal Control)
- b0-03 = 8 (Set Main Frequency Source to use PID)
- C0-00 = 0 (PID Setting Source set use C0-01)
- C0-01 = 20% (PID Digital Setting as % of target Level – 1m target level of max 5m level = 20%)
- C0-03 = 1 (PID Feedback Source = AI2)
- C0-04 = 1 (PID Action Direction – set as Reverse Action – determines the positive and negative effects of PID)
- b5-12 = 2 (Set AI2 Minimum Value) – (transmitter range = 4 to 20mA, so 4mA in a range from 4-20mA corresponds to a value of 2 if the range is 0 to 10)
- b5-14 = 10 (Set AI2 Maximum Value) – (transmitter range = 4 to 20mA, so 20mA (at 5m) in a range from 4-20mA corresponds to a value of 10 if the range is 0 to 10)
Sleep/WakeUp settings:
- b2-24 = 30 (Dormant Frequency)
- b2-25 = 30 (Dormant Delay Time)
- b2-26 = 31 (WakeUp Frequency)
- b2-27 = 10 (WakeUp Delay Time)
For other similar scenarios please also 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 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.
– To set up a EMHEATER VSD Restart (Delayed) after Low Current Protection Condition Occurred (Dry Run Protection Reset), please see the relevant FAQ entry Here.
