York YCAS0130 - Manual (Page 132)

132 YORK INTERNATIONAL
FORM 201.19-NM1 (204)
1.13 ANTI-RECYCLE TIMER
The programmable Anti-Recycle Timer allows the user
to select the compressor anti-recycle time to best suit
their needs. Motor heating is a result of inrush current
when the motor is started. This heat must be dissipated
before another start takes place or motor damage may
result. The anti-recycle timer assures that the motor has
suffi cient time to cool before it is restarted.
An adjustable timer allows for the motor cooling, but
gives the user the ability to extend the anti-recycle
tim er to cut down on cycling. In some applications,
faster com pres sor start response is necessary and shorter
anti-recycle times are required. These needs should be
kept in mind, but whenever possible the timer should
be ad just ed for the longest period of time tolerable.
600 sec onds is recommended, although 300 seconds
provides adequate motor cooling time. Longer periods
will al low more heat dissipation, reduce cycling, and
pos si bly in crease motor life. See Section 8.2, page 166
for pro gram ming of the anti-recycle timer.
1.14 ANTI-COINCIDENCE TIMER
The Anti-Coincidence Timer assures that 2 systems
do not start simultaneously. This assures that inrush
cur rent is kept to a minimum. A 60 second time delay
will al ways separate motor starts. This timer is not
pro gram ma ble.
1.15 EVAPORATOR PUMP CONTROL
Dry contacts are provided which transition (close)
when the Daily Schedule is calling for chiller opera-
tion, the unit switch is on, and power has been applied
to the Micro Panel for 30 sec onds. If for some reason
the evaporator pump contacts have been closed to run
the pump and a power loss or Daily Schedule shuts the
pump down (contacts open), the contacts will not reclose
for any reason until 30 sec onds has elapsed after power
re-application or 30 sec onds have elapsed between a
Daily Schedule shut down and restart.
If the Daily Schedule is not used, (On/Off times equal
00:00) the contacts will be closed at all times.
1.16 COMPRESSOR HEATER CONTROL
Each compressor has its own heater. The heater will be
off whenever the compressor is running. As soon as the
compressor shuts off, the heater will turn on and stay on
for 5 minutes. After 5 minutes has elapsed, the heat er will
shut off if the discharge temperature rises above 150 °F
(66°C) and will turn on when the dis charge tem per a ture
is equal to or less than 150 °F (66°C).
1.17 EVAPORATOR HEATER CONTROL
The evaporator heater is controlled by ambient tem-
per a ture. When the ambient temperature drops below
40°F (4°C), the heater is turned on when the com pres sors
are turned off. When the temperature rises above 45°F
(7°C), the heater is turned off. An under voltage condi-
tion will keep the heater off until full voltage is restored
to the system. The heater will provide freeze protection
to -20°F (-28°C).
115VAC power must remain “ON”
through CB3 for freeze pro tec tion.
Oth er wise, the evap o ra tor must be
drained.
1.18 PUMPDOWN (EEV) CONTROL
Each compressor undergoes a pump down on shut-
down. This as sures that liq uid re frig er ant does not
enter the com pres sor on start-up, elim i nat ing the need
for recycling pump down, sav ing en er gy and re duc ing
com pres sor starts and wear.
On start-up, the controls unload the com pres sor and im-
mediately energize the pilot solenoid on the electronic
expansion valve. Normal operation commences without
pumpdown.
On shutdown, the microprocessor controls unload the
compressor, the pilot solenoid on the electronic expan-
sion valve is de-energized, and the Econ o miz er Liquid
Supply Solenoid Valve is de-energized. The compressor
continues to op er ate until it either pumps down to the
Micro Panel Contents
Remote evaporator applications equipped with
thermostatic TXV and Liquid Line solenoid will also
pump down on shutdown.