Trane LPC Install And Operation Instructions Download

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LPC-SVX01C-EN

Operation

general
information

Table O-GI-6.

Binary input functions & locations

Tracer AH540

Tracer AH541

factory

field

input

terminal

power

label

function

IN 7

TB37-1 IN

J37

IN7

low-temp detection or coil defrost

24 Vdc

TB37-2 GND

ground

IN 8

TB38-1 OUT

J38

IN8

run/stop

24 Vdc

TB38-2 GND

ground

IN 9

TB39-1 OUT

J39

IN9

occupancy or generic

24 Vdc

TB39-2 GND

ground

IN 10

TB40-1 OUT

J40

IN10

supply fan status

24 Vdc

TB40-2 GND

ground

IN 11

TB41-1 OUT

J41

IN11

filter status

24 Vdc

TB41-2 GND

ground

IN 12

TB42-1 OUT

J42

IN12

exhaust fan status or coil defrost

24 Vdc

TB42-2 GND

ground

Note 1 When configured as a generic binary input, it has no direct effect on controller operation.

IN7: Low-temperature detection or coil
defrost

Binary input IN7 can be configured either
as a low-temperature detection
input or a coil defrost input.

Low-temperature detection

When configured as a low-temperature
detection input, IN7 protects the
coils of hydronic units. A low-
temperature-detection device
(freezestat) connected to the input
detects the low temperature. The Tracer
AH540/541 controller can protect the coil
using one binary input. When the
controller detects the low-temperature-
detection signal, the controller generates
a Low Temp Detect diagnostic, which
disables the fan, opens all unit
water or steam valves, and closes the
outdoor air damper (when present).

The low-temperature detection device
can be automatically or manually reset.
However, you must manually reset the
Low Temperature Detect diagnostic to
clear the diagnostic and restart the unit.
See “Resetting diagnostics” for instruc-
tions on clearing controller diagnostics.

Table O-GI-7. Low Temperature Detection Controller Operation

Diagnostic

Fan

Cool Output

Heat Output

Face & Bypass

Outdoor Air Damper

Low Temperature

Off

Open

(Note 1)

Face

Closed

Detection

Note 1: When steam is the source of heat, the heat valve is cycled open and closed when the controller is shut down on a

Low Temp Detect latching diagnostic. Cycling the steam valve helps prevent excessive cabinet temperatures. See steam
valve cycling in the Sequence of Operation section for further details.

Coil defrost

Binary input IN7 can be configured as a
coil defrost input in direct expansion
(DX) cooling applications when a binary
device is used to detect low evaporator
refrigerant temperatures. When the DX
coil refrigerant temperature drops below
the detecting device threshold and the
device output changes states, the Tracer
AH540/541 controller disables all DX
cooling until the frost condition is cleared.
DX cooling operation automatically
resumes when the binary input is normal.
For more information regarding coil
defrost operation, see “Coil defrost
binary input.”

Note: Binary input IN12 can also be
configured as a coil defrost input.

Table O-GI-8. Coil defrost binary input
configuration

Configuration

Contact closed

Contact open

not used

normal

normally closed

normal

DX cooling

disabled

normally open

DX cooling disabled normal

ON/CANCEL buttons on the zone sensor

Momentarily pressing the ON button on
the zone sensor during unoccupied mode
places the controller in occupied bypass
mode for 120 minutes. You can adjust the
number of minutes the Tracer AH540/541
is placed in the occupied bypass mode by
using the Rover service tool. The
controller remains in occupied bypass
mode until the override time expires or
until you press the CANCEL button on the
zone sensor.

If the building automation system sends
an unoccupied mode command to the
controller and ON button on the zone
sensor is pressed, the controller goes to
occupied bypass and communicates back
to the building automation system that its
effective occupancy mode is occupied
bypass.

If the controller is in the unoccupied
mode, regardless of the source (the
building automation system or a hard-
wired occupancy binary input), pressing
the ON button causes the controller to go
into the occupied bypass mode for the
duration of the configured occupied
bypass time.

Binary inputs

The Tracer AH540/541 controller has six
binary inputs. Each binary input
associates an input signal of 0 Vdc with
closed contacts and 24 Vdc with open
contacts. If the wired binary device has
closed contacts, a multimeter should
measure less than 1.0 Vdc across the
binary input terminals. If the binary input
has opened, a multimeter should
measure greater than 20 Vdc across the
binary input terminals.

Table O-GI-6 describes the function of
each of the binary inputs. For an explana-
tion of the diagnostics generated by each
input, see the “Diagnostics” section.