Lennox CHA16, Руководство по обслуживанию

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Page 17
In 20 ton and larger units, T1 is used only to supply 24VAC
power to the pilot control circuit and all 24VAC devices other
than the contactors and transformer T18 is used to supply
24VAC power to the contactors.
FIGURE 10
BLUE
YELLOW
ORANGE
RED
BLACK
PRIMARY SECONDARY
TRANSFORMER T1 208/230V SHOWN
208
VOLTS
230 VOLTS
4-Transformer T18 (2553, 2753, 3003 only)
Transformer T18 is a line voltage to 24VAC transformer
used in 20 ton and larger units. T18 is identical to trans
former T1 and is used to supply 24VAC power to the con
tactors.
5-Transformer T3 (all 460V and 575V units)
460 (G) and 575 (J) voltage units use a line voltage to 230V
autotransformer to power the combustion air blower. The
autotransformer is connected directly to line voltage and is
powered at all times. It has an output rating of 0.5A. In units
over 12.5 ton capacity, T3 is located in the heating control
box in the heating section.
6-Transformer Fuse F1 (all units)
T1 transformer is equipped with an integral fuse connected in
series with the blue secondary voltage wire. The fuse may be
accessed outside the transformer and is rated 3.5A.
7-Condenser Fan Motor Fuse F10
(2553, 2753, 3003 only)
Line voltage fuses F10 are used to provide overcurrent
protection to all condenser fans (and optional power ex
haust fans) in the unit. The fuses are rated at 20A in
208/230V units and 15A in all others.
8-Unit Line Voltage Fuses F16
(1853, 2553, 2753, 3003)
Line voltage fuses F16 are used to provide overcurrent
protection to all line voltage components in the unit (except
compressors, crankcase heaters and optional electric
heat). The fuses are rated at 35A in 208/230V units and
30A in all others.
9-Circuit Breaker CB4, CB5
(1603 Y voltage only)
Circuit breaker CB4 provides overcurrent protection to
condenser fan B4 in 12.5 ton units and CB5 provides
overcurrent protection to condenser fan B5. Both cir
cuit breakers are twopole 240V manual reset switches
with a 15A rating.
10-Compressor Contactor K1 (all units)
K1 is a 24V to line voltage contactor used to energize the
first compressor (B1) in response to first stage cooling de
mand. All units use threepoledoublebreak contactors for
threephase operation with a 24VAC coil.
NOTE-Contactor K1 is energized by the thermostat
control system. Depending on the control system
installed, the contactors may or may not be immediately
energized upon demand. Refer to the operation se
quence for the control system installed.
11-Compressor Contactor K2 (all units)
K2 is a 24V to line voltage contactor used to energize the
second compressor (B2) in response to cooling demand.
All units use threepoledoublebreak contactors for three
phase operation with a 24VAC coil. In 1853 units, contac
tor K2 is used for the second first stage compressor. In all
other units, K2 is used to energize the second stage com
pressor.
In 1603 and 1853 units, K2 is energized after a 30 second
delay is initiated by time delay DL15. The time delay is used
to stagger the electrical load and limit the effects of electri
cal inrush on unit components.
12-Compressor Contactor K14 (1853 only)
K14 is a 24V to line voltage contactor used to energize the
3rd compressor (B13) in response to second stage cooling
demand. Contactor K14 is identical to contactor K1. All units
use threepoledoublebreak contactors.
13-Condenser Fan Contactor K10
(all units except 1353)
K10 is a 24V to line voltage contactor used to energize both
condenser fans (B4 and B5) in response to demand. Both
condenser fans are energized with the first compressor upon
receiving a cooling demand. Both fans operate throughout all
cooling (compressor) demand. All units use threepole
doublebreak contactors with a 24VAC coil.
14-Condenser Outdoor Fan Contactor K68
(2553, 2753, 3003 only)
CHA16 20 ton and larger units are equipped with separate
condenser fan contactors for each stage of cooling. K68 is
identical to K10. In units equipped with two condenser fan
contactors, K10 operates with first stage circuit on a call for
first stage cooling and K68 operates with second stage circuit
on a call for second stage cooling.