IM710 13
Field Wiring
The following are descriptions of the various options and
features that may require field wiring to the MicroTech II
controller. Refer to the job plans and specifications and the
as-built wiring schematics. For a typical set of wiring sche-
matics refer to Figure 14 through Figure 20. For complete,
exact component designations and locations, refer to the leg-
end supplied with the unit.
For more information on the electrical installation, refer to
the applicable unit installation manual (Refer to Table 2 on
page 3).
Field Output Signals
The following output signals may be available for field con-
nections to any suitable device:
●
Outside Air Damper Output (MCB-BO2)
●
Fan Operation Output (MCB-BO3)
●
Remote Alarm Output (MCB-BO4)
●
VAV Box Output (MCB-BO12)
●
Pump Start Output (CCB1-BO3 or CCB2-BO3)
The Remote Alarm Output and Fan Operation Output are
available on all units. The VAV Box Output is available only
on VAV units.
Outside Air Damper
The Remote Damper Output (MCB-BO2) supplies 24 VAC
to terminal 119 on the field terminal block (TB2) when the
output is on. To use this signal, the coil of a field supplied
and installed 24 VAC pilot relay must be wired across termi-
nals 119 and 117 on TB2. When this output is on, 24 VAC is
supplied from the T3 control transformer through output
relay MCB-BO2 to energize the field relay. Refer to the as-
built wiring diagrams or the “Output Schematic: Actuator
Control” on page 36
For control of units with return air, the Remote Damper Out-
put is in the Close (Off) position and the Airside economizer
minimum position is set to zero, if any of the following is
true:
●
Unit is in the Off state.
●
Unit is in the Start Initial state
●
Unit is in the Recirc state
●
Unit is in the Morning Warmup state
●
Unit is operating during the Unoccupied period due to
Night Setback or Night Setup
For control of units with 100% outside air, the Remote
Damper Output is in the Open (On) position during the Start
Initial period, and it remains in the Open (On) position during
all operating stages. This output remains in the Open (On)
position after the fan is turned Off until 30 seconds after the
Airflow Switch digital input indicates loss of airflow. This
keeps the outside air dampers open in case there is a failure or
external override that keeps the fan running after it is turned
off by MicroTech. If the fan is running with the MicroTech
controls bypassed, the Damper output would NOT be On.
The economizer is driven closed when the unit is off.
Fan Operation Output
The Fan Operation Output (MCB-B03) supplies 24 VAC to
terminal 116 on the field terminal block (TB2) when the out-
put is on. To use this signal, the coil of a field supplied and
installed 24 VAC pilot relay must be wired across terminals
116 and 117 on TB2. When the output is energized, 24 VAC
is supplied from the T3 control transformer through output
relay MCB-B03 to energize the field relay. Refer to the as-
built wiring diagrams or to “Output Schematic: Actuator
Control” on page 36.
The Fan Operation Output (MCB-BO3) can be used to control
field equipment that depends on fan operation (field installed
isolation dampers, VAV boxes, etc.) This output is turned on at
the beginning of the Startup operating state and remains on
during fan operation. The fans remain off during the Startup
operating state allowing time for equipment such as isolation
dampers to open prior to the starting of the fan. The duration
of the Startup operating state is adjustable by setting the Start
Init= parameter in the Timer Settings menu on the keypad.
When the unit is shut off this output remains on for 30 seconds
after the airflow switch stops sensing airflow. This output is on
whenever the airflow switch senses airflow.
Remote Alarm Output
The Remote Alarm Output (MCB-B04) supplies 24 VAC to
terminal 115 on the field terminal block (TB2) when the out-
put is on. To use this signal, the coil of a field supplied and
installed 24 VAC pilot relay must be wired across terminals
115 and 117 on TB2. When this output is on, 24 VAC is sup-
plied from the T3 control transformer through output relay
MCB-B04 to energize the field relay. Refer to the as-built
wiring diagrams or to “Output Schematic: Actuator Control”
on page 36.
The action of this output depends on the setup of each of the
possible alarms. The output is on continuously (field relay
energized) when there are no active alarms within the unit
controller. Each alarm is then configured to cause the output
CAUTION
The total VA of all field-mounted relays must
exceed 15 VA and they must have a 24 VAC
Class 2 coil.
CAUTION
The total VA of all field-mounted relays must
exceed 15 VA and they must have a 24 VAC
Class 2 coil.
CAUTION
The total VA of all field-mounted relays must
exceed 15 VA and they must have a 24 VAC
Class 2 coil.
To Next Page
Loading...
Need help?
General
