PCU12005 datasheet(83/96 Pages) REDLION

83 / 96 page

OUTPUT LEAKAGE CURRENT

The AL1 and AL2/OP2 outputs of the PCU have an RC Network (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.

The Snubber Network is specifically designed with a capacitor and resistor

connected in series and installed across relay contacts. The network will have

a small amount of AC leakage current even when the PCU’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 only occur in unusual applications (such as with a relay with unusually

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 the Bezel Assembly from the case (see

Removing

Bezel Assembly, page 5). The snubbers are located on the Option PCB (on the

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

edge of the Option PCB. They are green in color and have color code stripes of

yellow, violet, black and gold. There will be markings on the PCB close to the

resistors that say “SNUB1” and “SNUB2” for AL1 and AL2/OP2

respectively. Using a pair of diagonal cutters, cut both leads of the

appropriate resistor and remove it from the unit. Be sure to remove the resistor

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 it’s 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 at

right, depending on model ordered.

-75-

Figure 40, Snubber Locations

PCU12005 Datasheet(PDF) 83 Page - Red Lion Controls. Inc