During a DMM test of N.C contacts, what does a reading of no voltage during activation indicate?

When conducting a DMM (Digital Multimeter) test on normally closed (N.C.) contacts, a reading of no voltage during activation indicates that the circuit is functioning as intended. In a normally closed configuration, the contacts should allow current to flow when they are in their default state (closed). When the contacts are activated, they should open, which prevents current from flowing. Therefore, if the DMM reads no voltage during the activation, it shows that the contacts have successfully opened, interrupting the circuit, and confirming that they are functioning correctly.

This situation highlights the importance of understanding the operational state of N.C. contacts, as they serve the specific purpose of maintaining a completed circuit until a signal triggers them to open. A zero voltage reading is precisely what one would expect during this activation phase, confirming that the switch mechanism is effective in disrupting the electrical path.

The other interpretations of the reading, such as those suggesting a malfunctioning DMM or the circuit being open or closed, do not align with the operational characteristics of N.C. contacts during the activation phase. Knowing this helps technicians diagnose and analyze pneumatic systems accurately.