[FONT="]I have a float switch from the bottom of a still that, according to the ohmmeter works fine. . The controller tries to pass 24V through the switch and feed it into a PLC input to determine if there is water or not. [/FONT]
[FONT="]OPEN CONDITION: When the float is at the bottom, there is infinite resistance – the meter makes no noise and reads 0L, which is the same as when the leads are separated and not touching. [/FONT]
[FONT="]CLOSED CONDITION: When the float is up the stem a bit, I get 0.5 ohms resistance and the meter indicates that the switch is closed.[/FONT]
[FONT="]PROBLEM: When 24V is passed through the switch, it is always ON=CLOSED CONDITION regardless of the float position Why? I have confirmed the problem condition with 2 different voltage sources.[/FONT]
[FONT="]OBSERVATION: If I use the 24V through the switch and an ammeter and an LED I see that the CLOSED switch position is passing 10.6mA and lighting the LED. The OPEN position is passing 12.3 mA and also lighting the LED.[/FONT]
[FONT="]I have attached a photograph of the switch. The brand is not known and it has no markings. I have taken it apart more than is shown in the photo and where the wires go into the switch housing, the housing is rusty.[/FONT]
[FONT="]OPEN CONDITION: When the float is at the bottom, there is infinite resistance – the meter makes no noise and reads 0L, which is the same as when the leads are separated and not touching. [/FONT]
[FONT="]CLOSED CONDITION: When the float is up the stem a bit, I get 0.5 ohms resistance and the meter indicates that the switch is closed.[/FONT]
[FONT="]PROBLEM: When 24V is passed through the switch, it is always ON=CLOSED CONDITION regardless of the float position Why? I have confirmed the problem condition with 2 different voltage sources.[/FONT]
[FONT="]OBSERVATION: If I use the 24V through the switch and an ammeter and an LED I see that the CLOSED switch position is passing 10.6mA and lighting the LED. The OPEN position is passing 12.3 mA and also lighting the LED.[/FONT]
[FONT="]I have attached a photograph of the switch. The brand is not known and it has no markings. I have taken it apart more than is shown in the photo and where the wires go into the switch housing, the housing is rusty.[/FONT]