Typical Control Sequence, Normal Start - Carrier 16JT Series Start Up & Operation Manual

3-1 (ON) — Start Chiller
3-1 (OFF) — Stop Chiller
3-BZ — Buzzer Silencer
BZ — Alarm Buzzer
3-VP (ON) — Optional Start Vacuum Pump
3-VP (OFF) — Optional Stop Vacuum Pump
43-R — Remote Local Switch
GL — Chiller Running Lamp
HM — Running Hour Meter
OL1 — Low Flow, Low Chilled Water Temperature Lamp
OL2 — Hermetic Pump Fault Lamp
OL3 — Generator Fault Lamp
OL4 — Optional Vacuum Pump Fault Lamp
RL — Chiller Stopped Lamp
TIC — Temperature Indicating Controller
WL1 — Refrigerant High Level Lamp
WL2 — Dilution Operation Lamp
Fig. 12 — Typical Control Panel Door
LEGEND
1-23 — Auxiliary Relays
2T1 — Time Delay Relay
33W — Generator Level Control Relay
43-RV — Cycle-Guard Auto. Man.
88RP — Refrigerant Pump Starter
88SP1 — Solution Pump Starter, No. 1
88SP2 — Solution Pump Starter, No. 2 (Large Sizes Only)
88SSP — Solution Spray Pump Starter (Some Larger Sizes Only)
88VP — Optional Vacuum Pump Starter
EF1,2 — Fuses
MCB — Main Circuit Breaker
TB — Field Wiring Terminals
TR — Transformer
Fig. 13 — Typical Control Panel Components
Arrangement

Typical Control Sequence, Normal Start

(Fig. 10 and 14)
1. When power is supplied to the chiller control panel and
the chiller is not in operation, the Stop light (RL) is on.
2. To start up machine, the Cycle-Guard™ switch (43-RV)
should be placed in the AUTO. position.
When the Start button is depressed, start relay (3X) latches
the ready state. If the Local/Remote switch is in the local
position, the Run light (GL) also goes on and the run re-
lay (2X) energizes to start the chiller. If the switch is in
the remote position, the Run light will go on and 2X will
start the chiller only when the remote control start con-
tacts close.
The run relay (2X) also starts the chilled water pump if
it is tied into the chiller control circuit for auto. start/stop
and its water pump safety contacts are closed.
3. If the low load contacts (23C) in the temperature con-
troller are closed with a demand for cooling, the start re-
lays (1X1 and 1X2) are energized to turn off the Stop
light (RL) and lock out the shutdown dilution function
(62T1). Relay 1X2 also starts the cooling water pump and
cooling tower fan if they are tied into the chiller control
circuit for auto. start/stop and their interlocks and safeties
are closed.
4. When the chilled water flow switch (69CW) closes, the
pump interlock timer (2T1) energizes and closes its con-
tacts in about 2 seconds. If, at that time, the chilled water
and cooling water pump contacts (88EP and 88CP), and
the low-chilled water temperature safety (26CW) are all
closed, the system water pump safety interlock relay (CWX)
is energized.
When the absorber pressure switch relay (ABSX), ma-
chine pump safeties (26MX), and 1X1 contacts are also
closed, interlock relays (1Y1 and 1Y2) are energized for
self-latching and for normal operation of the refrigerant
and solution pumps, generator level control, and Cycle-
Guard operation.
5. If the safeties for the generator conditions (63GX) are also
closed, the safety device relay (4X) energizes to latch in
the safety interlock relay (4Y), and to lock out the safety
stop relays (30X1 and 30X2), and the alarm buzzer (BZ).
The 4X relay also switches the Cycle-Guard valve (20RV)
to automatic level switch control, and releases the capac-
ity control valve from the closed position. However, the
load limiter relay (LIX) is initially deenergized, keeping
the valve at a mid-open position for a soft start. After about
15 minutes, time delay relay 62T3 contacts close to en-
ergize LIX, releasing the capacity control valve to nor-
mal full range control, unless LIX remains deenergized
by the open contacts of the high refrigerant level relay
(33RHX).
If the solution level in the high-stage generator is not too
high for normal operation, as determined by the level con-
trol electrode and relay (33W), the generator pump(s) (88SP)
starts when 1Y2 closes. If it is too high, the pump(s) will
start after the generator solution has fallen to a normal
level.
If the evaporator refrigerant level is above the low-level
safety switch (33RL) when start relay 1X1 is energized,
the refrigerant pump start delay timer (62T2) energizes.
After approximately 5 minutes, the refrigerant pump (88RP)
starts if 1Y2 is also closed. If the evaporator level is too
low, the timer is not energized until the generator can con-
centrate the solution enough to raise the refrigerant level
above the low-level switch.
14