ST500 | Analogue sensors – How are they connected and parameterised?

There are a variety of sensors (e.g. pressure sensors, flow sensors, temperature sensors, …) that output their measurement results in the form of analogue signals. The ST500 frequency inverters have two analogue inputs with terminals AI1 and AI2 referred to terminal GND.

The inverter accepts at these terminals:

0V to +10V DC voltage
0mA to 20mA direct current.

Jumpers J3 (AI1) and J4 (AI2) are provided to select whether to control by current or voltage. If the jumpers between 1&2 are closed, the current is measured, with 2&3 the voltage. The factory setting for AI1 and AI2 was voltage measurement until mid-2015, since then the factory setting for AI2 is current measurement.

Settings for the analogue inputs are found under parameters F1.12 – F1.24. With the help of these parameters, the dependence of the setting value on the analogue input value can be adjusted. For example, the 2V base offset for a 4-20mA sensor can be set here. Parameters F7.50, F7.51, F1.25, F1.31 and F1.32 allow further settings for the analogue terminals.

The signals at the terminals can then be used to control the inverter, depending on the application. For example, an input voltage of 0V-10V can be used to change the setpoint frequency.

In parameter F0.03, select the source for the setpoint frequency.
In parameter FA.01, select the source for torque control.

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