Arc extinction kits

Case 1: Switching inductive loads

Nowadays, almost exclusively ECGs are switched. Therefore, our detectors are optimised for capacitive loads. High inrush currents occur with capacitive loads. Zero-crossing switching protects the relay from damage. However, one consequence is that inductive loads, such as conventional ballasts, low-loss ballasts or contactors, can cause problems. When the detector is switched off, a so-called pulse is generated that can influence the passive infrared (PIR) sensor. As a result, the detector detects a new movement and switches the lighting on again.

Instead of analogue PIR sensors, digital PIR sensors are now used that are less sensitive to such interference.

If a detector due to an inductive load switches the lighting on again immediately after it has been switched off, this can be remedied by an additional extinguishing element. For this purpose, an arc extinction kit must be installed at the detector output L' and the neutral conductor N as close as possible to the detector.

Case 2: L‘-monitoring

Detectors can be connected in parallel at the L' output. However, light measurement also plays a role with detectors: A detector only switches on the lighting if the measured brightness is below the set value, i.e., the detector calculates too dark. If the lighting is switched on by a detector M1, it is then too bright for a detector M2 connected in parallel. As soon as the movement passes into the detection range of M2, the latter will no longer switch on the light. Despite movement, the system (detector M1) will switch off the lighting after the follow-up time has elapsed. Only then can M2 react, as it is now dark again.

Switching off the light for a short time is not desired as there is still movement within the jointly monitored area. The L' monitoring recognises whether a detector connected in parallel has already switched L'. In this case, M2 deactivates its light measurement and functions as a slave device for the follow-up time that is currently running.

However, L' monitoring is susceptible to coupling of voltages (inductive/capacitive residual voltages) on the L' line. Coupling of voltages can occur when lines are laid in parallel. An arc extinction kit can filter out this interference voltage. For this purpose, it must be installed between L' and the neutral conductor N as close as possible to the detectors connected in parallel.

Case 3: Master/slave circuit

Interference voltages on the slave line (R) influence the master/slave circuit. A slave device only sends its information to the master when the R line is "free", i.e., when no other device is transmitting. If the interference voltage at the slave device is too high, it will no longer send signals. A movement in the detection range of the slave device will then not cause the master to switch on the lighting, even if the ambient brightness is below the value set on the master device. An arc extinction kit in the vicinity of the slave device between the R line and the neutral conductor N can provide a remedy.

Due to an interference voltage at the master/slave input, the lighting is switched on permanently. In this case, the arc extinction kit is installed near the master device, also between the R line and the neutral N conductor.

An interference voltage on the slave line is indicated by the regular flashing of the slave LED in the absence of movement.

However, interference voltages can also occur if the slave device sends information about detected movement in intervals that are too short. In this case it is recommended to set the pulse pause at the slave device to 9 seconds (factory setting).

Case 4: Push-button input

Interference voltages can also occur on the push-button line (S). These signal to the detector that the push-button for manual operation is permanently pressed.

An arc extinction kit between the S line and the neutral conductor N close to the detector can also remedy this.