JOHNSON CONTROLS
14
FORM 160.43-NM4
ISSUE DATE: 11/12/2012
SECTION 3 - TESTING AND ADJUSTMENTS
CUTOUT SETPOINT TESTING AND
CALIBRATION
The LPCO CUTOUT setpoint is calibrated first, then
the switch DEADBAND is set.
CUTOUT on pressure fall: refer to Table 1 for setpoint.
1.
Remove enclosure cover first by removing the one
captive screw located on the front of the cover Re-
fer to Figures 2 and 3.
2. Disconnect the three wires (47, 48 and 49) from
the LPCO switch terminals and secure out of the
way.
3. Connect an Ohm meter, to measure continuity,
between the LPCO switch Common and Normal-
ly Open terminals. At atmospheric pressure the
switch contacts are made between the Common
and Normally Open terminals and open between
the Common and Normally Closed terminals.
4. Using the controlled vacuum source, slowly lower
the pressure to the LPCO toward vacuum. Note
at what exact vacuum pressure the switch trans-
fers opening between the Common and Normally
Open terminals. As the pressure falls below the
control CUTOUT setpoint the switch transfers
to be made between the Common and Normally
Closed terminals and open between the Common
and Normally Open terminals.
5. Carefully and slowly, loosen the hose connection
at the vacuum source and allow the pressure in the
line to the LPCO slowly rise to atmospheric pres-
sure. Retighten the hose connection at the vacuum
source.
6. If the CUTOUT setpoint noted in step 4 is below
or above the allowable CUTOUT setpoint range
called out in Table 1, then make an adjustment to
the setpoint screw. The set point adjusting screw,
labeled “A” in Figure 4, is located beneath the
switch and is turned to adjust the set point. Use
a 1/4 inch open-end wrench to keep plunger, la-
beled “B” in Figure 4, from turning. Using a 3/16
inch open-end wrench, turn the adjustment screw
towards the right (counter-clockwise) to increase
set point (towards full vacuum) or towards the left
(clockwise) to decrease set point (towards 0 psig).
7. Repeat steps 4, 5, and 6 until the noted CUT OUT
setpoint is within the allowable range.
8.
Once the CUTOUT set point is verified or cali
-
brated, then proceed to the switch DEADBAND
calibration procedure.
SWITCH DEADBAND TESTING AND
CALIBRATION
CUTIN on pressure rise: CUTIN equals CUTOUT plus
DEADBAND settings. Refer to Table 1 for settings.
1. Connect an Ohm meter, to measure continuity,
between the LPCO switch Common and Normal-
ly Open terminals. At atmospheric pressure the
switch contacts are made between the Common
and Normally Open terminals and open between
the Common and Normally Closed terminals.
2. Using the controlled vacuum source, slowly low-
er the pressure to the LPCO toward vacuum. As
the pressure falls below the control CUTOUT
setpoint the switch transfers to be made between
the Common and Normally Closed terminals and
open between the Common and Normally Open
terminals.
3. Carefully and slowly, loosen the hose connection
at the vacuum source and allow the pressure in the
line to the LPCO to rise very slowly toward atmo-
spheric pressure. Note at what exact vacuum pres-
sure the switch transfers, again, closing between
the Common and Normally Open terminals. As
the pressure rises above the control CUTIN (CU-
TIN equals cutout plus deadband settings) the
switch transfers to be made between the Common
and Normally Open terminals and open between
the Common and Normally Closed terminals. Al-
low the pressure to rise to atmospheric. Retighten
the hose connection at the vacuum source.
4. If the CUTIN setting noted in step 3 is below or
above the allowable DEADBAND range called
out in Table 1, then make an adjustment to the
switch DEADBAND setting. To adjust the dead-
band, turn the adjustment wheel on the underside
of the switch, labeled “C” in Figure 4, using the
switch Ground (green) mounting screw as an in-
dex. As the letters advance, the deadband widens.
Turn the adjustment wheels towards the right
(counterclock wise) to decrease deadband (to-
wards letter “A”) or towards the left (clockwise)
to increase deadband (towards letter “F”).
5. Repeat steps 3, 4, and 5 until the noted CUTIN is
within the allowable DEADBAND setting range.
