Zelio SR3B261FU

Hi PLC experts!

I need advice and your suggestions. I have Schneider's PLC Zelio SR3B261FU Smart relay. It is used to run 2 water pumps.

INPUTS
IN1 - AUTO P1
IN2 - MANUAL P1
IN3 - AUTO P2
IN4 - MANUAL P2

Inputs are connected through selector switch (1-0-2) and physically cannot be selected MANUAL and AUTO in the same time for a pump.

Inputs IN1 and IN2 are fine and reacting on switching very fine.
Issue is with IN3 and IN4. They are ALWAYS ON (BOTH together). Selector switch is tested and is ok. I removed wires from IN3 and IN4 but they still didn't change value (ON).

I tried to reset voltage powering relay ("plc") and after boot up, inputs are ok and in state OFF. But after some time they turn ON by itself. I tried to measure voltage between Inputs and GND and here are results:

IN1 - GND - 38VAC
IN2 - GND - 38VAC
IN3 - GND - 39,9 VAC
IN4 - GND - 39,9 VAC

It is little bit strange as it should be very near 0VAC if I'm right. From datasheet it can be seen that Voltage state 0 is guaranteed <= 40 V for discrete input. IN3 and IN4 are very very close to the limit value and it can cause an issue.

If I force Inputs to change bit value, it works good.

Do you have any more suggestions what to test and to check? Ground fault? Zelio faults?

Thank you!

This is only a guess, it appears that the unit is faulty. As a test to see if it is somehow picking up some stray voltages, connect a small 110 vac incandescent bulb or pilot lamp from the suspected inputs to ground or neutral to see if the input will go low or the lamp will light up. If the lamp does light up with no other wires connected to them, then, just try replacing the unit. Also, the unit or power source may not be properly grounded.

What is your supply voltage to the zelio?

chud said:

what is your supply voltage to the zelio?

Click to expand...

230vac