Protective Devices; Compressor Protection - Bryant Preferred 551J Service And Maintenance Instructions

Resetting Alarm and Trouble Condition Trips:
Manual reset is required to restore smoke detector systems to Nor-
mal operation. For installations using two sensors, the duct smoke
detector does not differentiate which sensor signals an alarm or
trouble condition. Check each sensor for Alarm or Trouble status.
Clear the condition that has generated the trip at this sensor. Then
reset the sensor by pressing and holding the reset button (on the
side) for 2 seconds. Verify that the sensor's Alarm and Trouble
LEDs are now off. At the controller, clear its Alarm or Trouble
state by pressing and holding the manual reset button (on the front
cover) for 2 seconds. Verify that the controller's Alarm and Trou-
ble LEDs are now off. Replace all panels.
TROUBLESHOOTING
Controller's Trouble LED is On
1. Check the Trouble LED on each sensor connected to the
controller. If a sensor's Trouble LED is on, determine the
cause and make the necessary repairs.
2. Check the wiring between the sensor and the controller. If
wiring is loose or missing, repair or replace as required.
Controller's Trouble LED is Flashing
1. One or both of the sensors is 100% dirty.
2. Determine which Dirty LED is flashing, then clean that sen-
sor assembly as described in the detector cleaning section.
Sensor's Trouble LED is On
1. Check the sensor's Dirty LED. If it is flashing, the sensor
is dirty and must be cleaned.
2. Check the sensor's cover. If it is loose or missing, secure
the cover to the sensor housing.
3. Replace sensor assembly.
Sensor's Power LED is Off
1. Check the controller's Power LED. If it is off, determine
why the controller does not have power and make the nec-
essary repairs.
2. Check the wiring between the sensor and the controller. If
wiring is loose or missing, repair or replace as required.
Controller's Power LED is Off
1. Make sure the circuit supplying power to the controller is
operational. If not, make sure JP2 and JP3 are set correctly
on the controller before applying power.
2. Verify that power is applied to the controller's supply
input terminals. If power is not present, replace or repair
wiring as required.
Remote Test/Reset Station's Trouble LED Does Not Flash
When Performing a Dirty Test, but the Controller's Trouble
LED Does
1. Verify that the remote test/station is wired as shown in
Fig. 35. Repair or replace loose or missing wiring.
2. Configure the sensor dirty test to activate the controller's
supervision relay. See "Changing Sensor Dirty Test
Operation."
Sensor's Trouble LED is On, But the Controller's Trouble
LED is OFF
Remove JP1 on the controller.

PROTECTIVE DEVICES

Compressor Protection

OVERCURRENT
The compressor has internal linebreak motor protection. Reset is
automatic after compressor motor has cooled.
OVERTEMPERATURE
Each compressor has an internal protector to protect it against ex-
cessively high discharge gas temperatures. Reset is automatic.
HIGH PRESSURE SWITCH
The system is provided with a high pressure switch mounted on
the discharge line. The switch is stem-mounted and brazed into the
discharge tube. Trip setting is 630 psig ± 10 psig (4344 ± 69 kPa)
when hot. Reset is automatic at 505 psig (3482 kPa).
LOW PRESSURE SWITCH
The system is protected against a loss of charge and low evapora-
tor coil loading condition by a low pressure switch located on the
suction line near the compressor. The switch is stem-mounted.
Trip setting is 54 psig ± 5 psig (372 ± 34 kPa). Reset is automatic
at 117 ± 5 psig (807 ± 34 kPa).
SUPPLY (INDOOR) FAN MOTOR PROTECTION
PERSONAL INJURY HAZARD
Failure to follow this caution can result in personal injury.
Disconnect all electrical power when servicing the fan motor.
Apply appropriate lockout/tag-out procedures.
Motors with 2.9 and 3.7 bhp are equipped with an internal over-
temperature or protection device. The type of device depends on
the motor size. See Table 8.
The High Static option supply fan motor is equipped with a pilot-
circuit Thermik 1 combination overtemperature/ overcurrent pro-
tection device. This device resets automatically. Do not bypass
this switch to correct trouble. Determine the cause and correct it.
The Thermik device is a snap-action overtemperature protection
device that is embedded in the motor windings. The Thermik can
be identified by two blue wires extending out of the motor control
box. It is a pilot-circuit device that is wired into the unit's 24-v
control circuit. When this switch reaches its trip setpoint, it opens
the 24-v control circuit and causes all unit operation to cease. This
device resets automatically when the motor windings cool. Do not
bypass this switch to correct trouble. Determine the cause and cor-
rect it.
The External Overload Breaker is an overcurrent device used on
motors with a horsepower rating of 4.7 hp or greater. This is a spe-
cially-calibrated circuit breaker that is UL recognized as a motor
overload controller. When the current to the motor exceeds the cir-
cuit breaker setpoint, the device opens all motor power leads to the
motor, shutting the motor down. Reset requires a manual reset at
the overload switch. This device (designated IFCB) is located on
the side of the supply fan housing, behind the fan access panel.
The Must Hold and Must Trip values are listed on the side of the
External Overload Breaker.
Table 8 — Overcurrent Device Type
MOTOR SIZE (bhp)
1.7
2.4
2.9
3.7
4.7
TROUBLESHOOTING SUPPLY FAN MOTOR OVER-
LOAD TRIPS
The supply fan used in 551J units is a forward-curved centrifugal
wheel. At a constant wheel speed, this wheel has a characteristic
that causes the fan shaft load to DECREASE when the static pres-
sure in the unit-duct system increases and to INCREASE when
the static pressure in the unit-duct system decreases (and fan
1. Thermik is a registered trademark of Thermik Geratebau GmbH.
31
CAUTION
OVERLOAD DEVICE
Internal Linebreak Automatic
Internal Linebreak Automatic
Thermik Automatic
Thermik Automatic
External (circuit breaker)
RESET
Manual