Output Leakage Current
TheAL1 andAL2/OP2 outputsofthe TCUhave anRCNetwork (Snubber)
on the Normally Open contacts. High energy noise spikes are generated
whenever current through an inductive load (such as motors, solenoids or
relay coils) is interrupted. This noise may interfere with the unit doing the
switching and other nearby equipment causing erratic operation and
accelerate relay contact wear.
TheSnubber Networkisspecifically designedwith acapacitorand resistor
connected inseries andinstalled across relaycontacts. Thenetwork willhave
a small amount of AC leakage current even when the TCU’s Relay Module is
“off”. The leakage current is 2.1 mA nominal at a line voltage of 120 VAC,
and 4.3 mA nominal at 240 VAC respectively. Leakage current may cause
some loads to stay on or to turn on when the Relay Module is turned off. This
would onlyoccur inunusual applications(such aswith arelay withunusually
low holding current or an LED). The leakage current may be eliminated by
disabling the snubber,however, doing so will degrade the EMC performance
of the unit.
First determine which output is associated with the leakage current: either
AL1 or AL2/OP2. Remove theB ezel Assembly fromthe case (see Removing
BezelAssembly,page 5).The snubbersarelocated onthe OptionPCB (onthe
right side of the unit when viewed from the front). The snubbers consist of a
capacitor and a resistor. The two resistors are located along the upper rear
edgeof theOptionPCB.Theyaregreenincolorand havecolorcodestripesof
yellow,violet, blackand gold.There willbe markings onthe PCBclose tothe
resistors that say “SNUB1” and “SNUB2” for AL1 and AL2/OP2
respectively. Using a pair of diagonal cutters, cut both leads of the
appropriateresistorandremoveitfromtheunit. Besuretoremovetheresistor
for only the problem alarm channel; leave the other channel’s snubber
functional in case it is needed.
The above stated leakage currents are valid when using the Relay Module
(OMD00000). The Triac Module (OMD00001) has its own built in snubber
and will introduce additional leakage current into the circuit. The Triac
Module has leakage current of 2.1 mA nominal at a line voltage of 120 VAC,
and 4.3 mA nominal at 240 VAC.
Note: The Snubber Network will be in one of the two configurations shown
above, depending on model ordered.
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