How can I use a multimeter to measure a NAMUR limit switch?

To measure a NAMUR limit switch using a multimeter, you need to follow these steps: 1. **Set the multimeter**: First, set the multimeter to the resistance setting or the diode test mode, as NAMUR limit switches operate based on changes in resistance. 2. **Connect the multimeter**: Connect the two test leads of the multimeter to the two terminals of the NAMUR limit switch. A NAMUR limit switch usually has two wires: one is the signal wire and the other is the ground wire. 3. **Read the value**: Observe the meter reading when the limit switch is not activated. In its static (inactive) state, the NAMUR limit switch typically exhibits a specific resistance value or is in an open circuit condition. 4. **Activation switch**: Manually activate the limit switch to simulate its operating condition. When the NAMUR limit switch is activated (i.e., the contacts close), the multimeter should show a relatively low resistance value or a condition close to a short circuit. 5. **Compare readings**: By comparing the readings before and after activation, it is possible to determine whether the NAMUR limit switch is functioning properly. If the resistance value decreases significantly when it is in the activated state, it indicates that the limit switch is working properly. If the reading does not change, it may indicate a fault with the limit switch. Remember, NAMUR limit switches operate with very low currents; therefore, when making measurements, ensure that the correct setting is used on the multimeter to avoid applying excessive current, which could damage the limit switch. .

The standard method is to connect a multimeter in series with the circuit to measure current, at 1mA or 3mA. Voltage can also be measured in parallel; it is generally around 4V or 8V.

Is it to supply an 8V DC power to the limit switch? One of the wires is broken and connected to the red and black test leads of the multimeter respectively?

The measurement method you mentioned is applicable when the limit switch has no power supply, right? Can the condition of a limit switch be determined by changes in resistance?

The measurement method you mentioned is applicable when the limit switch has no power supply, right? Determine the condition of the limit switch by observing changes in resistance

Yes, it needs to be powered by a safety barrier. Without power supply, only resistance can be measured; in that case, one has to rely on the parameters provided by various manufacturers, but these aren’t guaranteed and make it difficult to make an accurate judgment.

Without power supply, what change can there be in the resistance value? Go and check out how the switch for the Namur signal works.