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•
The second method is through the Keypad / Dis-
play. Press the right arrow key > until the display
shows [Faults] and press ENTER, use the right
arrow key > to scroll down to "Off – On Resets".
Press ENTER. You will be asked to enter the
password. Enter the password and press ENTER.
Use the INC key to change OFF to ON and press
ENTER. The "Alarm" will reset. Press ENTER
and then INC to turn the "Off – On Resets" back
to OFF.
Dirty Filter (Alarm)
The unit can have a pressure switch installed (DFS) that
monitors the pressure drop across the fi lters. The switch
is factory set to close at 0.6 inwc. The switch has a fi eld
adjustable set point range of 0.17 to 5.0 inwc.
switch is normally open and closes on pressure increase.
The input to the control is at IN-12 – Terminals 7 and 8
of the Expansion I/O control. When the circuit is closed
between these two connection points the control waits
one minute and then issues a "Dirty Filter Alarm".
If this circuit opens, the control will wait one minute
and then discontinue the Alarm. The unit continues
normal operation even though a "Dirty Filter Alarm"
is present.
Duct High Static (Fault / Alarm)
All VAV units will be equipped with a Duct Static High
Pressure (DHS) switch. The setting of the Duct Static
High Pressure switch is 3.0 inwc. The switch has a
fi eld adjustable set point range of 0.17 to 5.0 inwc. The
Duct Static Pressure switch input can be found at IN-8
– terminals 15 and 16 of the control. If the Duct Static
High Pressure switch opens for ten seconds, it turns off
the supply air blower and terminates all compressor
operation. The control will register a "Duct High
Pressure Fault" as long as the Duct Static High Pressure
switch is open. As soon as the Duct Static High Pressure
switch closes, the unit will return to the start up mode
and go into normal operation. The control maintains
a running total of the number of times the Duct Static
High Pressure switch opens. Each time the Duct Static
High Pressure switch opens the counter increases by
one. Every hour the control decreases the fault count by
one. The current condition of the "Fault" (ON - active
/ OFF – inactive) and the current count can be viewed
using the Keypad / Display. Use the right arrow key >
to scroll to "Faults" and press the ENTER key. Press
the right arrow key > to scroll down to "Duct Hi Pres".
JOHNSON CONTROLS
The display will tell you Off or On and # Trips. If the
accumulated fault count reaches fi ve, the control will
declare a "Duct High Pressure Alarm". All operation
of the unit is terminated and the unit is locked out.
External Safety
The unit is designed to allow the connection of an
External Safety Shutdown Switch. The input to the unit
is at IN-14 – terminals 11 and 12 of the I/O Expansion
Control Board. If the External Safety Switch circuit
opens for ten seconds, it turns off the supply air blower
and terminates all compressor operation. The control
will register an "External Safety Fault" as long as the
switch is open. As soon as the switch closes, the unit
will return to the start up mode and go into normal
operation.
The control maintains a running total of
The
the number of times the External Safety circuit opens.
Each time the circuit opens the counter increases by
one. Every hour the control decreases the fault count by
one. The current condition of the "Fault" (ON - active
/ OFF – inactive) and the current count can be viewed
using the Keypad / Display. Use the right arrow key > to
scroll to "Faults" and press the ENTER key. Press the
right arrow key > to scroll down to "External Safety".
The display will tell you Off or On and # Trips. If the
accumulated fault count reaches fi ve the control will
declare a "External Safety Alarm". All operation of the
unit is terminated and the unit is locked out.
Fan Failure (Alarm)
The unit is equipped with a pressure switch to verify
supply air blower operation (AFS). The Air Flow
Switch is normally open and closes at 0.2 inwc. The
switch has a fi eld adjustable set point range of 0.17 to
5.0 inwc. When the switch closes it makes a circuit at
IN-7 – terminals 13 and 14 of the Unit Control Board.
A "Fan Failure Alarm" can occur under two different
scenarios:
•
On start up, if this circuit is not closed within two
minutes from the start of the supply blower the
control will initiate a "Fan Failure Alarm" and
locks out the operation of the unit.
•
If supply fan operation is verifi ed and the unit is
in normal operation and the airfl ow switch circuit
opens, the control waits three minutes ten seconds
and if the circuit is still open the control declares
a "Fan Failure Alarm" and locks out the unit.
FORM 145.05-NOM2 (807)
97
8
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