FORM 150.24-NM27
YORK INTERNATIONAL
73
PUMPDOWN CONTROLS (Recycling Pumpdown
EPROMs)
*
Pumpdown control will pump down a system to the suc-
tion pressure cut-out whenever the compressor shuts
down on a normal shutdown. Additionally, a recycling
pumpdown is employed on an as needed basis to as-
sure that liquid does not accumulate in the evaporator
on an OFF system, while cold chilled liquid is flowing
through the evaporator. Since pumpdown at start-up is
not employed, the liquid line solenoid valve will open im-
mediately when a compressor starts.
Pumpdown on shutdown will pump a system down
whenever a system shuts down, except in two circum-
stances. A pumpdown will not occur whenever a fault
causes a shutdown or when UNIT rocker switch is
turned off. Pumpdown will continue until the suction pres-
sure falls below the suction pressure cut-out. If the pres-
sure never drops below the cut-out, pumpdown will con-
tinue until a 3 minute timer has expired.
During pumpdown, the following STATUS message will
be displayed:
The PUMPING DOWN message indicates that the re-
spective compressor is presently in the process of pump-
ing the system down. The compressor will either be in a
recycling pumpdown or in a pumpdown prior to shut-
down when this message is displayed. The message
will disappear when the compressor shuts off.
Recycling pumpdown is initiated while a compressor
is off, able to run, and is in a No Cooling Load state. It
can be initiated 45 minutes after either of the following
two conditions are met:
1. Sat Suction Temp > LCHWT 1.5°F
and
Ambient Temp > LCHWT 6°F
2. The compressor has been idle for 2 hours and
Suction Pressure is greater than the cut-out.
The 45 minute timer assures that excessive pumpdowns
do not occur.
After 120 pumpdowns, uninterrupted by a cooling start,
the system will cease to pump down. Pumpdowns will
begin again after a cooling start occurs. This is to pre-
vent oil loss in the system. However, if one system
reaches 120 pumpdowns while the other system is run-
ning for cooling, the running (lead) compressor will be
shut off if the off (lag) compressor is available for start.
At this point, the lead compressor will pump down and
shut off while the lag compressor starts and assumes
the lead. The previous running compressor will now have
120 pumpdowns available.
A pumpdown failure fault will occur if a system performs
3 unsuccessful pumpdowns in a row. Unsuccessful
assumes that the system was not able to pump down to
the suction pressure cut-out in 3 minutes. The system
will require a manual reset to restart. The following is an
example of this safety message.
NOTE: Under some circumstances, a pumpdown may
occur when a compressor is called to come on
for cooling. If this occurs, the compressor will
restart to provide cooling after the pumpdown is
complete and the anti-recycle timer times out.
Recycling pumpdown will increase the number of starts
logged in the micropanel; however, it will have no effect
upon the life of the compressors.
Pumpdown Safety
* *
The Pumpdown Safety assures that a compressor does
not run unless it completes a proper pumpdown. This
prevents operation of a refrigerant system which has a
leaking liquid line solenoid valve.
On shutdown, the system must pump down to the suc-
tion pressure cut-out within 300 seconds or the system
will shut down. If the system performs 3 unsuccessful
pumpdowns in a row, the system will fault and lock out.
An example of the pumpdown fault display message is
shown below:
S Y S # 1
P U M P D O W N
F A I L
S Y S # 2
P U M P D O W N
F A I L
S Y S # 1
P U M P I N G
D O W N
S Y S # 2
P U M P I N G
D O W N
*
Recycling Pumpdown control applies to chillers with 031-01652-001 (CRCP Version) EPROMs.
** The Pumpdown Safety only applies to chillers with 031-01652-001 (CRCP Version) EROMs.
Содержание YCRJ45E00
Страница 29: ...FORM 150 24 NM27 YORK INTERNATIONAL 29 CONTROL CIRCUIT With I O Expansion Board LD02106 ...
Страница 30: ...30 YORK INTERNATIONAL FIG 9 SYSTEM WIRING ...
Страница 31: ...FORM 150 24 NM27 YORK INTERNATIONAL 31 LD02678 ...
Страница 33: ...FORM 150 24 NM27 YORK INTERNATIONAL 33 LD02357 MOTOR TERMINAL BOX WIRING WITH MODEL 31AA MOTOR PROTECTOR ...
Страница 34: ...34 YORK INTERNATIONAL FIG 10 CONNECTION DIAGRAM LD02358 MICROPANEL CONNECTION DIAGRAM WITHOUT EXPANSION BOARD ...
Страница 35: ...FORM 150 24 NM27 YORK INTERNATIONAL 35 LD02679 ...
Страница 36: ...36 YORK INTERNATIONAL MICROPANEL CONNECTION DIAGRAM With I O Expansion Board LD02107 ...
Страница 37: ...FORM 150 24 NM27 YORK INTERNATIONAL 37 LD02108 ...