38
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.
CAUTION
!
Motors with 2.9 and 3.7 bhp are equipped with an
overtemperature or protection device. The type of device
depends on the motor size. See Table 6.
The High Static option supply fan motor is equipped with
a pilot--circuit Thermik combination overtemperature/
overcurrent protection 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 imbedded 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 24V control circuit.
When
this switch reaches its trip setpoint, it opens the 24V
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 correct 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 specially--calibrated circuit breaker that
is UL recognized as a motor overload controller. When
the current to the motor exceeds the circuit 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.
Troubleshooting Supply Fan Motor Overload Trips
The supply fan used in 48HC 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 pressure in the unit--duct
system increases and to INCREASE when the static
pressure in the unit--duct system decreases (and fan
airflow rate increases).
Motor overload conditions
typically develop when the unit is operated with an access
panel removed, with unfinished duct work, in an
economizer--open mode, or a leak develops in the duct
system that allows a bypass back to unit return opening.
Table 6 -- Overcurrent Device Type
Motor Size (bhp)
Overload Device
Reset
1.7
Internal Linebreak
Automatic
2.4
Internal Linebreak
Automatic
2.9
Thermik
Automatic
3.7
Thermik
Automatic
4.7
External
(Circuit Breaker)
Manual
Condenser Fan Motor Protection
The condenser fan motor is internally protected against
overtemperature.
Control Circuit, 24V
The control circuit is protected against overcurrent
conditions by a circuit breaker mounted on control
transformer TRAN. Reset is manual.
The factory--installed PremierLink Controller includes the
supply--air temperature (SAT) sensor. The outdoor air
temperature
(OAT)
sensor
is
included
in
the
FIOP/accessory EconoMi$er 2 package.
Refer to Fig. 46 for PremierLink connection locations.
NOTE
: Refer to
PremierLink
t
Installation, Start--Up
and Configuration Instructions.
Have a copy of this
manual available at unit start--up.
48H
C
Содержание 48HC D17 Series
Страница 76: ...76 APPENDIX IV WIRING DIAGRAMS C12615 Fig 76 48HC D17 D28 Control Diagram 208 230 3060 460 575 3 60 48HC...
Страница 77: ...77 APPENDIX IV WIRING DIAGRAMS C12616 Fig 77 48HC D17 D28 Power Diagram 208 230 3 60 48HC...
Страница 78: ...78 APPENDIX IV WIRING DIAGRAMS C12617 Fig 78 48HC D17 D28 Power Diagram 460 3 60 48HC...
Страница 79: ...79 APPENDIX IV WIRING DIAGRAMS C12618 Fig 79 48HC D17 D28 Power Diagram 575 3 60 48HC...
Страница 80: ...80 APPENDIX IV WIRING DIAGRAMS C14061 Fig 80 48HC D17 D28 Control Diagram with Humidi MiZer 48HC...
Страница 81: ...81 APPENDIX IV WIRING DIAGRAMS C12620 Fig 81 48HC D17 D28 Power Diagram 208 230 3 60 with Humidi MiZer 48HC...
Страница 82: ...82 APPENDIX IV WIRING DIAGRAMS C12621 Fig 82 48HC D17 D28 Power Diagram 460 3 60 with Humidi MiZer 48HC...
Страница 83: ...83 APPENDIX IV WIRING DIAGRAMS C12622 Fig 83 48HC D17 D28 Power Diagram 575 3 60 with Humidi MiZer 48HC...
Страница 85: ...85 APPENDIX IV WIRING DIAGRAMS C13766 Fig 85 PremierLinkt System Control Wiring Diagram with Humidi MiZer 48HC...
Страница 86: ...86 APPENDIX IV WIRING DIAGRAMS C13767 Fig 86 RTU OPEN Wiring Diagram 48HC...
Страница 87: ...87 APPENDIX IV WIRING DIAGRAMS C13768 Fig 87 RTU OPEN Wiring Diagram with Humidi MiZer 48HC...