FORM 150.24-NM27
YORK INTERNATIONAL
53
AVERAGE CURRENT UNLOAD
The purpose of AVERAGE CURRENT UNLOAD is to pro-
vide adequate motor cooling and to prevent the motor from
faulting on high motor current. The motor current unload
feature only unloads a compressor by a
single step
. This
provides more cooling to the motor and at the same time
still attempts to pull the water temperature down.
Unloading will only occur when a compressor is running
with at least one step of loading above a fully unloaded
state. This feature will not, under any circumstances,
shut a compressor off.
Whenever Motor Current Unloading is activated, the com-
pressor will stay in the unloaded state for 5 minutes.
After the 5 minute time period, the micro will look at
motor current once again. If motor is 25% below the pro-
grammed Motor Current Unload point, the compressor
will be allowed to reload, if water temperature allows.
To program the Motor Current Unload, key in the desired
value and press the ENTER key. The new value will be
entered into memory and the display will advance to the
next user programmable limit.
The micro will accept a range of programmable values
between 80-105% for the unload point. A setting of 100%
is recommended for the unload point.
NOTE: When programming values from 80-99%, it is
first required to key in a 0. Example: 090%.
SUCTION PRESSURE UNLOAD
The SUCTION PRESSURE UNLOAD point is a pro-
grammable limit designed to assure that suction gas
returning to the compressor is cool enough to provide
adequate compressor cooling.
If the suction pressure rises to the suction pressure un-
load pressure, the micro will automatically totally unload
the affected compressor which reduces motor heating.
Reloading will occur when the suction pressure drops to 10
PSIG below the programmed unload pressure and will incre-
ment one stage at a time as dictated by the loading timers.
This safety will only come into action on a very hot water
start with related high system suction pressure. Its sole
purpose is to prolong motor life.
To program the SUCTION PRESSURE UNLOAD, key in
the desired value and press the ENTER key. The new
value will be entered into memory and the display will
advance to the next user programmable limit.
The micro will accept a range of programmable values
between 80-105 PSIG for the unload point.
NOTE: When programming values from 80-99 PSIG, it is
required to first key in a 0. Example: 085 PSIG.
RATE CONTROL TEMP
The RATE CONTROL TEMP establishes a temperature
range over which the micro may override normal system
loading timers and react to actual rate of change of re-
turn and leaving water temperature. This temperature
range is slightly above the setpoint with its band width
being programmable. This control works in conjunction
with the RATE SENSITIVITY which is also programmable.
These controls allow the chiller to adapt to a full range of
applications. Depending on how the controls are set up,
the chiller can be adapted to provide maximum response,
demand limiting/energy saving, or reduced loader and
compressor cycling.
Typically this value should be
programmed for 00.1°F. When programming values
like 00.1°F, it is first required to key in 00. Example:
00.1°F.
Additional details for programming this control will
be discussed in the SELECTION OF RETURN OR LEAV-
ING CHILLED LIQUID CONTROL Section (Page 57).
ANTI RECYCLE TIME
The ANTI RECYCLE TIME selection allows the user to
select the compressor anti-recycle time to best suit his
needs. Motor heating is a result of inrush current when
the motor is started. This heat must be dissipated be-
fore another start takes place or motor damage may re-
sult. The anti-recycle timer assures the motor has suffi-
cient time to cool before it is again restarted.
An adjustable timer allows for the motor cooling required,
but gives the user the ability to extend the timer to cut
down on cycling. In some applications fast compressor
start response is necessary, in others it is not. These
needs should be kept in mind and the timer should be
adjusted for the longest period of time tolerable. Although
300 seconds is adequate motor cooling time, longer pe-
riods will allow even more heat dissipation, reduce cy-
cling, and possibly increase motor life.
To program the ANTI-RECYCLE TIME, key in the de-
sired value and press the ENTER key. The new value will
be entered into memory and the display will advance to
the next user programmable limit.
The micro will accept a range of programmable values
between 300-600 seconds for this operating control.
LEAVING WATER TEMP CUT-OUT
R A T E
C O N T R O L
T E M P
=
0 8 . 0
F
A N T I
R E C Y C L E
T I M E
=
6 0 0
S E C S
L E A V I N G
W A T E R
T E M P
C U T O U T
=
3 6 . 0
F
* *
S U C T I O N
P R E S S U R E
U N L O A D
=
0 9 0
P S I G
A V E R A G E
C U R R E N T
U N L O A D
=
1 0 0
% F L A
*
* This message only applies to chillers with 031-01096-001 and early versions of 031-01652-001 EPROMs.
* * This message only applies to chillers with later versions of 031-01652-001 (CRCP Version) EPROMs.
Summary of Contents for YCRJ45E00
Page 29: ...FORM 150 24 NM27 YORK INTERNATIONAL 29 CONTROL CIRCUIT With I O Expansion Board LD02106 ...
Page 30: ...30 YORK INTERNATIONAL FIG 9 SYSTEM WIRING ...
Page 31: ...FORM 150 24 NM27 YORK INTERNATIONAL 31 LD02678 ...
Page 35: ...FORM 150 24 NM27 YORK INTERNATIONAL 35 LD02679 ...
Page 36: ...36 YORK INTERNATIONAL MICROPANEL CONNECTION DIAGRAM With I O Expansion Board LD02107 ...
Page 37: ...FORM 150 24 NM27 YORK INTERNATIONAL 37 LD02108 ...
