Transistor Used as a Power Supply

Introduction to signal transmission for proportional control

OBJECTIVES:

1. To construct a 4-20 mA control loop and verify the loop current control signal using the fluke 773 milliamp process clamp meter.

2. To verify that the 4 to 20 mA control signal functions independently of power supply voltage.

3. To verify the output signal voltage at the receiver resistance in a 4 to 20 mA current transmission loop.

4.

Materials and Equipment

1. Controller

2. DMM(Digital multi meter)

3. 250 Ohm Resistor (Approx. 273.4 Ohms )

4. DC power supply

5. Fluke 773 milliamp process clamp on meter

6. Voltage receiver

7. Transmitter

PROCEDURE A. Verify the 4-20 mA control signal

1. Set the loop power supply voltage at its maximum value of 24V.

2. Connect the 4-20 mA transmitter simulator to form a current loop using the 250 Ohm test resistor as shown in Fig # 1. The mA function of many digital mutimeteres is suitable for measuring the loop current.

3. With the power supply switched on adjust the loop adjustment control to give the maximum loop current of 20 mA, we measured and recorded the voltage at the receiver resistor.

PROCEDURE B. Demonstration of the proper use of the Fluke 773 .

1. Verify the ammeter reading of the loop current with the fluke 773 miliamp process clamp meter

2. Readjust