Figure 4-6 Maximum Setpoints For Auto-Sentry S Controller, Psig - Gardner Denver EBB BB-7.5 HP Operating And Service Manual

should read "0" pressure in the left window,
and –––– current sump temperature in the
right window.
Step 12: Move the circuit board slide switch back to
the "set" position (right). You may now pro-
ceed with normal start up procedure.
A. To readjust, the slide switch
must be in the "+" position.
B. If procedure is repeated, the
transducer zero operation may
be bypassed by not pressing
"Stop–Reset" while the dashes
(––– –––) are displayed.
C. Transducer must be zeroed only
while at zero "0" pressure, or in-
valid shutdowns may occur.
LEAD–LAG OPERATION OF TWO COMPRES-
SORS – The Auto–Sentry S controller provides the ca-
pability of true lead–lag operation without the need to
NAMEPLATE
FULL LOAD
OPERATING
PRESSURE
100
125
150
175
Load setpoint cannot be set within 8 psi of the unload setpoint.
Minimum operating pressure is 60 – 65 PSIG.
FIGURE 4–6 – MAXIMUM SETPOINTS FOR AUTO–SENTRY "S" CONTROLLER, PSIG
purchase any additional equipment and without compli-
cated interconnecting wiring.
Follow these steps to operate two compressors in a
lead–lag arrangement:
Step 1: Program load and unload pressure setpoint
on both units to the same value. For exam-
ple: Compressor "A" load at 92 PSI; unload
at 100 PSI. Compressor "B" load at 92 PSI;
unload at 100 PSI. See page 19, this section,
for complete information on programming
the setpoints.
Step 2: Operate one compressor in the "Auto Lead"
mode. This compressor will now be the
"Lead" or "Base Load" compressor.
Step 3: Operate the second compressor in the "Auto
Lag" mode. This compressor will now be the
"lag" or "trim" compressor. It will automatical-
ly be brought on line, if required, by a large air
demand. After the demand is satisfied, the
lag unit will unload, time out and stop, ready
to start again when needed.
Step 4: Periodically reverse the roles of the units by
changing each unit's mode of operation from
"Auto Lead" to "Auto Lag" and vice versa. By
using the hourmeters on the control panel to
schedule the mode changes, the operating
hours can be kept as close as possible,
equalizing machine wear and minimizing
maintenance costs.
CONTROL SYSTEM
PRESSURE (PSI)
LOAD
92
117
142
167
13–8–612 Page 21
UNLOAD
100
125
150
175