Carrier 17/19EX Demand Limiting, Machine T imers

vane response to chilled wate r temperature b elow deadband plus control point. It can be
adjusted on the LID from a set ting of 2 to 10, and the def aul t setting is 6.0. Increa sing either of
these settings will ca us e t he vanes to respond slow er than a lower setting .
The
PROPORTIONAL ECW GA IN
can be adjusted at th e LID display from a s etting of 1.0 to
3.0, with a default settin g of 2.0. Increase this s et ting to increase guide vane response to a
change in entering chil led water temperatu r e. The proportional ban ds and gain may be viewed/
modified on the Equipment S ervice3 table.
Demand Limiting
The PIC will r espond to the
ACTIVE DEMAND LIMIT
set point by limiting th e opening of the
guide vanes. I t will compare the set point to either
COMPRESSOR MOTOR LOAD
or
COMPRESSOR MOTOR CURRENT
(percentage), de pending on how the control is conf igured
for the
DEMAND LIMIT SOURC E
which is acc essed on the SERVICE1 table. The default
setting is current limiting.
Machine T imers
The PIC maintains 2 runtime clocks, known as
COMPRESSOR ONTIME
and
SERVICE ON-
TIME. COMPRESSOR ONTIME indicates the total lifetime compressor run hours. T his timer
can register up to 500,000 hours be fore the clock tu rns back to zero. The
SERVICE ONTIME
is
a resettable timer that can be used to indicate the hours since the last service visit or any other
reason. The time can be cha nged through th e LID to what ever value i s desired. Thi s timer can
register up to 32,767 hours before it rolls over to zer o.