FACAULTY OF APPLIED TECHNOLOGY Deparrtment of Electronics Τ.Ε.Ι. of PIRAEUS FACAULTY OF APPLIED TECHNOLOGY Deparrtment of Electronics Laboratories Power Electronics & Control

Liquid level control. Level control system Photo of System System Description  The system under control is a liquid tank equipped with a filling valve and a draining pipe with a valve. This is an elementary hydraulic 1st order system.

Liquid level control system schematic Block diagram of close loop system Mathematical model. qin(t) [litres/min] qout(t) [litres/min]

Experiments in the laboratory 1. Measurement of the pump motor starting voltage The electric motor-pump not rotate until a certain minimum voltage value is reached. This range is called “dead range”.

2. Pump interface block: Measurement of the pump interface output as a function of the reference level voltage. The Pump Interface is a no linear stage 3.Loop gain amplifier block: Measurements for the calculation of the block gain.

3.Loop Pump and pump interface as one block: Measurements for the calculation of the block gain.

4. Liquid level sensor (floater) block: measurements for the calculation of the block gain.

5. Tank and draining pipe as one block: measurements for the calculation of the block time constant.

6. Closed loop system: Recording of the system dynamic response, h(t) 6. Closed loop system: Recording of the system dynamic response, h(t). Study of the effect of the loop amplifier gain Kc on the liquid level error.

Examples of Experiments on the Internet Loop gain amplifier block: Measurements for the calculation of the block gain.

6. Closed loop system: Recording of the system dynamic response, h(t) 6. Closed loop system: Recording of the system dynamic response, h(t). Study of the effect of the loop amplifier gain Kc on the liquid level error. Step 1 the stages loop gain & Pump Interface in saturation the system works in no linear reason Step 2 the stage Pump Interface in saturation the system work in no linear reason Step 3 the system is at the steady state all the stages works in linear reason.

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