Hey guys! My Siemens SXL-EX decided about a year ago that it doesn’t like my Notifier NWS-24, and still it continually causes a NAC trouble when it is connected. I have tried several times to correct the issue but had no luck. Everything is wired correctly, the strobe operates fine on 24V alone, and I checked it for polarity and resistance with my multimeter, but the trouble remains.
This is also the only time I have seen a trouble other than a battery trouble at all while I have had this panel, so I know it is isolated to this device. Every other device I have used on this system works perfectly, except the NWS-24.
Has anybody who owns this strobe had a similar problem with it and their panel and know how to correct it?
I haven’t found any oddities in the strobe’s operation, wiring it backwards does nothing and there is no continuity. When the trouble would come in I shut the panel down to make changes and never activated the NAC during the trouble condition to prevent damage. I handle all my devices carefully, but I agree with you, especially this one due to its rarity.
No other device has ever caused a trouble on this panel.
The NAC is filtered DC, and I always program the coding to continuous for strobes.
Edit: Also as a note, the device causes a trouble on both NACs, not simultaneously, but only if it connected to that NAC.
I have seen this happen when a component in notification appliance breaks down and causes leakage through the appliance. If the leakage current is great enough the NAC will sense it as a short on the circuit. That causes a trouble condition on the panel.
If your multimeter is digital it has a “low power” ohmmeter circuit. This only puts about 0.3 volts across the device which is not enough voltage to read the leakage. The reason meter manufacturers use this circuit is so the meter can check resistors without removing them from circuit boards. The very low voltage will not turn on semiconductor junctions so the resistance reading will be true.
Two tests can be used.
connect only a EOLR to the NAC. Read and note the supervisory voltage across the circuit. Then connect the notification appliance in question to the circuit along with the EOLR. Measure the supervisory voltage again. If the voltage decreases the appliance is leaking.
Connect the notification appliance to the NAC or a 24 volt source in supervisory polarity with a current meter in series with it. The meter should read zero current through the device. A few micro-amps (if your meter reads that low) are acceptable. If there is more than that the device is leaking.
By doing this test I found there is indeed a leak through the device. I’ll solder some pigtail leads onto a diode so it can be wired in series with the device to correct it. Thank you very much Retired STR-SG.