AERCO BMS 168 - Manual (Page 14)

3.6 I
NTERLOCK
W
IRING
The BMS is equipped with two interlocks
designated Interlock 1 (INT 1) and Interlock
2 (INT 2). Since both interlocks must be
closed for the BMS to operate the boiler
plant, the associated wiring terminals are
jumpered, prior to shipment. If desired,
proving device switches can be connected
to either interlock in place of the jumper. If
used, interlock wiring connections are made
as described in the following paragraphs.
NOTE
If necessary, Interlock 1 can be
programmed to operate the boilers
only when the outside air
temperature falls below the system
start temperature. See para. 4.4.2
for details. Interlock 2 cannot be
programmed with this feature.
3.6.1 Interlock 1 Wiring
Interlock 1 is often used with auxiliary
equipment, such as air dampers or flow
switches. If used, connect the end proving
switch to INT 1 terminals 11 and 12 as
shown in the wiring diagram in Appendix I.
3.6.2 Interlock 2 Wiring
Interlock 2 is a general purpose interlock
which can be used with a variety of devices
or equipment or conditions that must be
proved prior to enabling the boiler plant. If
used, connect the end proving switch to INT
2 terminals 13 and 14 as shown in the
wiring diagram in Appendix I.
3.7 R
ELAY
W
IRING
The BMS contains a System Start Relay, a
Fault Alarm Relay and an Auxiliary Relay
which can be connected to external
monitoring or control devices. The contacts
for each of these relays are rated at 120
VAC, 5A and are fused internally at 5A with
replaceable fuses. The contact terminals
for these relays are shown in the wiring
diagram in Appendix I.
3.7 1 System Start Relay
The state of the System Start (SYS START)
relay contacts are controlled by the value
set for the SYS START TEMP function in
the Field Adjust Mode (para. 4.3.5). The
contacts are closed only when the outside
air temperature is less than the System
Start Temperature (SYS START TEMP)
which is set in the Field Adjust Mode. The
default for this temperature setting is 70°F.
3.7.2 Fault
Alarm Relay
The state of the Fault Alarm (FLT ALARM)
relay contacts are controlled by the option
selected by pressing the CONFIG SYS key
when in the Field Adjust mode (para.
4.3.16). Contact closure can be set to ALL
FAULTS, INTERLOCK 1, INTERLOCK 2, or
NO INTERLOCK.
3.7.3 Auxiliary
Relay
The state of the Auxiliary (AUX) relay
contacts are controlled by the AUX RELAY
CLOSE option selected when in the System
Configuration mode (para. 4.4.8). Contact
closure can be set to occur either when all
available boilers are at the maximum power
input or no boilers are available (all boilers
faulted or turned off).
NOTE
The SET BACK function is used only
if the header supply temperature will
be offset manually as described in
para. 4.3.13. Disregard para. 3.8 if
an automatic header temperature
reset schedule is used as described
in para. 4.3.12.
3.8 S
ET
B
ACK
The SET BACK terminals shown in the
wiring diagram in Appendix I are used only
when implementing a manually-controlled
header temperature offset. If used, connect
a dry contact switch across SET BACK
terminals 15 and 16 on JP3.
3-4