I-Unit Components - Lennox ZCC Series Unit Information

I-UNIT COMPONENTS

ELECTROSTATIC DISCHARGE (ESD)
Precautions and Procedures
CAUTION
Electrostatic discharge can affect electronic
components. Take precautions to neutralize
electrostatic charge by touching your hand
and tools to metal prior to handling the
control.
All 7.5 through 12.5 ton (26.3 through 44 kW) units are
configure to order units (CTO). The ZCC unit components
are shown in figure 1. All units come standard with remov-
able unit panels. All L1, L2 and L3 wiring is color coded; L1
is red, L2 is yellow and L3 is blue.
A-Control Box Components
ZCC control box components are shown in figure 2.
1-Control Transformer T1 all units
All use a single line voltage to 24VAC transformer mount-
ed in the control box. Transformer supplies power to con-
trol circuits in the unit. The transformer is rated at 70VA
and is protected by a 3.5 amp circuit breaker (CB8). The
208/230 (Y) voltage transformers use two primary voltage
taps as shown in figure 3, while 460 (G) and 575 (J) volt-
age transformers use a single primary voltage tap.
208/230V TRANSFORMER
BLUE
SECONDARY
PRIMARY
ORANGE
FIGURE 3
YELLOW
208 VOLTS
RED
230 VOLTS
BLACK
2-Terminal Strip TB1
All indoor thermostat connections will be to TB1 located in
the control area. For thermostats without "occupied " and
"unoccupied" modes, a factory installed jumper across ter-
minals R and OC should be in place.
3-Condenser Fan Capacitors C1 & C2
Fan capacitors C1 and C2 are used to assist in the start
up of condenser fans B4 and B5. Ratings will be on side
of capacitor or outdoor fan motor nameplate.
4-Compressor Contactor K1 & K2
All compressor contactors are two-pole, double-break
contactors with 24VAC coils. In all ZCC units, K1 and K2
energize compressors B1 and B2 in response to thermo-
stat demand.
5-Variable Speed Drive VFD A96
Units are equipped with a factory-installed supply air in-
verter (VFD). During cooling, the blower will operate at
one of three speeds depending on the demand. When de-
mand is low, the blower will operate at low speed. When
demand is higher, the blower will operate at either medium
or high speed depending on the cooling demand.
6-Condenser Fan Relay K10
Outdoor fan relay K10 is a DPDT relay with a 24VAC coil.
K10 energizes condenser fans B4 and B5.
7-Power Exhaust Relay K65 (PED units)
Power exhaust relay K65 is a DPDT relay with a 24VAC
coil. K65 is used in all ZCC units equipped with the option-
al power exhaust dampers. K65 is energized by the econ-
omizer enthalpy control A6, after the economizer dampers
reach 50% open (adjustable) When K65 closes, exhaust
fan B10 is energized.
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