MACHINE CONTROLS
Start-Stop Systems —
The type of start-stop system
is selected by the customer. The most commonly used sys-
tems are described below. Review the descriptions and de-
termine which type applies to your system.
SEMI-AUTOMATIC START-STOP — In this basic system,
auxiliary equipment is wired into the machine control cir-
cuit and the machine is started and stopped manually with
the machine’s Start and Stop buttons. Two variations are used:
With Pilot Relays — The coils for the chilled water and con-
densing water pump starters (or other auxiliary equipment)
are wired into the machine control circuit so that the aux-
iliary equipment operates whenever the machine operates.
The starter contacts and starter overloads remain in the ex-
ternal pump circuits. The flow interlocks for each pump are
also wired into the machine control circuit and must be closed
in order for the machine to operate.
With Manual Auxiliaries — With this system, the auxiliaries
must be started manually and independently from the ma-
chine start, and they must be operating before the ma-chine
can start. As with the pilot relay system above, the
flow interlocks are in the machine control circuit and must
be closed for the machine to operate.
FULL AUTOMATIC START-STOP — This system is ba-
sically the same as the semi-automatic system with pilot re-
lays described above. Machine and auxiliary start and stop,
however, are controlled by a field-supplied thermostat, timer,
or other automatic device, and the machine Start and Stop
manual switch and indicator lights remain in the START mode.
As with all the Start-Stop systems, the machine’s Start but-
ton must be depressed and released on initial start, and after
power interruption. After an abnormal shutdown, the Stop
button must be depressed to reset the circuit and silence the
alarm buzzer before depressing Start.
Control Wiring — See Fig. 10 and 11 for typical wiring
schematics and component identification.
NOTE: These schematics do not show all the options or varia-
tions that are available.
Control Panel — The control panel includes the con-
troller, switches, pilot lights, and relays that operate the ma-
chine (Fig. 12 and 13).
LEGEND FOR FIGURES 10 AND 11
1X1,2 — Start-Stop Relays
1Y1,2 — Shutdown Dilution Relays
2X — Run Relay
2T1 — Time Delay Relay, Chilled Water Flow
3-1 — Manual Start Switch Button
3-5 — Manual Stop Switch Button
3-BZ — Alarm Buzzer Stop Button
3-VP — Manual Vacuum Pump On-Off Buttons
3X — Auto Start Relay
4X — Safety Device Relay
4Y — Safety Interlock Relay
20RV — Cycle-Guard™ Valve
23C — Low Load Limit Switch
26CW — Low Chilled Water Temperature Limit
26GH — Generator Solution High-Temperature Limit
26MX — Hermetic Pump Fault Relay
26RP — Refrigerant Pump Motor High-Temperature LImit
26SH — Absorber Solution High-Temperature Limit
26SP1 — Solution Pump No. 1 Motor High-Temperature Limit
26SP2 — Solution Pump No. 2 Motor High-Temperature Limit
26SSP — Solution Spray Pump Motor High-Temperature LImit
30X1,2 — Safety Stop Interlock Relays
33RD — Refrigerant Dilution Level Switch
33RH — Refrigerant High-Level Switch
33RHX — Refrigerant High-Level Relay
33RL — Refrigerant Low-Level Switch
33RM — Refrigerant Mid-Level Switch
33RMX — Dilution Level Control Relay
33W — Generator Level Control Relay
43R — Remote-Local Switch
43RV — Cycle-Guard Auto.-Manual Selector Switch
51CP — Condensing Water Pump Overload
51CT — Cooling Tower Fan Overload
51EP — Chilled Water Pump Overload
51RP — Refrigerant Pump Overload Relay
51SP-1 — Solution Pump No. 1 Overload Relay
51SP-2 — Solution Pump No. 2 Overload Relay (Larger Sizes Only)
51SSP — Solution Spray Pump Overload Relay (Some Larger Chillers)
51VP — Vacuum Pump Overload Relay (Optional)
62T1 — Time Delay Relay, Shutdown Dilution
62T2 — Time Delay Relay, Refrigerant Pump Start-Stop
62T3 — Time Delay Relay, Capacity Control Soft Start
62T6 — Time Delay Relay, Solution Pump Start-Stop
63GH — Generator High-Pressure Limit
63GX — Generator Fault Relay
69CW — Low-Chilled Water Flow Switch
88EP — Chilled Water Pump Starter
88CP — Condensing Water Pump Starter
88CT — Cooling Tower Fan Starter
88RP — Refrigerant Pump Starter
88SP-1 — Solution Pump No. 1 Starter
88SP-2 — Solution Pump No. 2 Starter (Larger Chillers Only)
88SSP — Solution Spray Pump Starter (Some Larger Chillers)
88VP — Vacuum Pump Starter (Optional)
ABS — Absorber Pressure Switch
ABSX — Absorber Pressure Switch Relay
BZ — Alarm Buzzer
BZX — Alarm Buzzer Relay
CWX — Low Water Flow or Temperature Fault Relay
HM — Hour Meter
LIX — Load Limiter Relay
MCB — Main Circuit Breaker
RTD — Temperature Sensor
RY1 — Auxiliary System Run Relay
T1,T2 — Water Pump Time Delay Relay
TIC — Temperature Indicating Capacity Controller
TR — Transformer
Z—Surge Suppressor
Terminals on Control Panel Terminal Strip
Component Connection (Unmarked)
Component Connection (Marked)
External Terminal
GL — Run Light
OL1 — Low Water Flow or Temperature Alarm Light
OL2 — Hermetic Pump Fault Alarm Light
OL3 — Generator Fault Alarm Light
OL4 — Vacuum Pump Fault Alarm Light
RL — Stop Light
WL1 — Shutdown Dilution On Light
WL2 — High-Refrigerant Level Light
NOTES FOR FIG. 10
1. The following items are not by Carrier:
• Chilled water pump, condensing water pump starters and discon-
nects
• Rigid or flexible conduit and junction boxes for wire and piping;
coded, except as noted
2. Solution and refrigerant pump starters are across-the-line definite
purpose type.
3. Solution and refrigerant pump motors are hermetic, 3-phase and op-
erate ±10% of rated voltage.
Rated Voltage Hz (Cycle)
200/220 60
400/440 60
575 60
4. Controls are for 1-phase, 60 Hz, 110 v. The maximum permissible
current rating which all holding relays have is 12 amps inrush,
3 amps continuous, and 0.8 amps interruption. Make sure that the
wiring does not exceed above values.
10
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