Table of Contents
Advertisement
OPERATING SEQUENCE
Base Unit Controls
Indoor (Supply) Fan —
The indoor fan contactor (IFC) is remotely located at the
fan coil or fan section. If the thermostat fan operation is
selected as Continuous, the IFC is energized and the
indoor (supply) fan motor runs continuously. If the
thermostat fan operation is selected as Automatic, the IFC
will be energized on a call for Cooling or Heating; indoor
(supply) fan motor runs. When thermostat is satisfied, the
IFC is de-energized and indoor (supply) fan motor stops.
Cooling, Unit Without Economizer - -
Single Stage Units—
When thermostat calls for Cooling, terminal Y1 is
energized. The 575J's Defrost Board (DFB) receives this
input at P2-5. DFB issues 24-v outputs at OF, P3-7
(RVS1) and P3-10 (COMP1). The OF output energizes
outdoor fan relay (OFR); both outdoor fan motors start
and run. The output RVS1 energizes the reversing valve
solenoid (RVS); Reversing valve switches to Cooling
position.
Output PL3-10 (COMP1, 24-v) is received at CADM
terminal Y. If anti-recycle time delay period has not expired,
safety pressure switches are open, and/or lockout alarms are
active, CADM relay will remain open, preventing
compressor start. When safety pressure switches are closed
and CADM time delay expires, the CADM relay closes,
energizing Solenoid Valve Relay SVR and compressor
contactor C. SVR contacts close, energizing the external
liquid line solenoid valve. Solenoid valve LLSV opens.
Compressor contactor C closes, energizing the compressor
motor. Compressor starts and system runs in Cooling mode.
When space cooling load is satisfied, terminal Y1 is
de-energized. Compressor and outdoor fan motors stop.
Liquid line solenoid valve LLSV is de-energized and
valve closes. CADM begins its three-minute anti-recycle
time delay.
If either the Loss of Charge (LOC) Switch or High
Pressure Switch (HPS) opens while Y1 remains energized,
the compressor contactor C and relay SVR are
de-energized; compressor stops and liquid line solenoid is
de-energized (valve closes). CADM initiates a TRIP event
(cooling demand sensed at CADM terminal Y but no
current is measured at T1, T2, T3 motor sensors); CADM
relay opens and RED LED is illuminated. TRIP condition
maintains lockout of compressor operation until CADM is
manually reset. Reset CADM by cycling unit main power.
Reversing valve solenoid (RVS) is energized in Cooling
modes. This solenoid will remain energized until the next
Heating mode is initiated.
Cooling, Unit Without Economizer - -
Two- - Stage Units—
For two stage units, the 575J*07G/H uses a two- - stage
Copeland Ultratech Scroll compressor in conjunction with
a two- - stage Comfort Alert Module (CADM). The
575J*12G/H uses two compressors in tandem on a single
circuit in conjunction with two single- - stage Comfort Alert
Modules (CADM).
575J*07G/H
When thermostat calls for Stage 1 Cooling, terminal Y1 is
energized. The 575J's Defrost Board (DFB) receives this
input at P2- - 5. DFB issues 24- - v outputs at OF, P3- - 7
(RVS1) and P3- - 10 (COMP1). The OF output energizes
outdoor fan relay (OFR); both outdoor fan motors start
and run. The output RVS1 energizes the reversing valve
solenoid (RVS); Reversing valve switches to Cooling
position. Output PL3- - 10 (COMP1, 24- - v) is received at
CADM terminal Y. If anti- - recycle time delay period has
not expired, safety pressure switches are open, and/or
lockout alarms are active, CADM relay will remain open,
preventing compressor start. When safety pressure
switches are closed and CADM time delay expires, the
CADM relay closes, energizing Solenoid Valve Relay
SVR and compressor contactor C. SVR contacts close,
energizing the external liquid line solenoid valve.
Solenoid valve LLSV opens. Compressor contactor C
closes, energizing the compressor motor. Compressor
starts and system runs in Stage 1 Cooling mode.
When thermostat calls for Stage 2 Cooling, terminal Y2 is
energized. The 575J's Defrost Board (DFB) receives this
input at P2- - 4. DFB issues 24- - v outputs at OF, P3- - 8
(COMP2). Output PL3- - 8 (COMP2, 24- - v) is received at
CADM terminal Y2. CADM DC SOL terminal outputs
24- - vdc to the compressor loader plug (LDR) and the
compressor operates at full load capacity.
As space cooling load is satisfied, thermostat outputs Y2
and Y1 are sequentially de- - energized, removing 24- - v at
terminals Y2 and Y1. Compressor Loader plug is
de- - energized on Y2 opening. On Y1 opening, the
Compressor stops, all outdoor fan motors stop and SVR
relay is de- - energized. Liquid line solenoid valve is
de- - energized and valve closes. CADM begins its
three- - minute anti- - recycle time delay.
If either the Loss of Charge (LOC) Switch or High
Pressure Switch (HPS) opens while Y1 remains
energized,the compressor contactor C and relay SVR are
de- - energized; compressor stops and liquid line solenoid is
de- - energized (valve closes). CADM initiates a TRIP
event (cooling demand sensed at CADM terminal Y but
no current is measured at T1, T2, T3 motor sensors);
CADM relay opens and RED LED is illuminated. TRIP
condition maintains lockout of compressor operation until
CADM is manually reset. Reset CADM by cycling unit
main power. Reversing valve solenoid (RVS) is energized
in Cooling modes. This solenoid will remain energized
until the next Heating mode is initiated.
575J*12G/H
When thermostat calls for Stage 1 Cooling, terminal Y1 is
energized. The 575J's Defrost Board (DFB) receives this
input at P2- - 5. DFB issues 24- - v outputs at OF, P3- - 7
(RVS1) and P3- - 10 (COMP1). The OF output energizes
outdoor fan relay (OFR); both outdoor fan motors start
and run. The output RVS1 energizes the reversing valve
solenoid (RVS); Reversing valve switches to Cooling
28
Advertisement
Table of Contents
