Carrier 17/19EX Capacity Override (See Table 4)

There are 2 methods of ramp lo ading with the PIC. Ramp lo adi ng can be based on chille d
water temperature or on motor load.
1. Temperature ramp load ing limits the rate at whic h either leaving chilled wa ter or entering
chilled water temperature decreases by an operator-configured rate. The lowest
temperature ramp tab le will be used the first time the machine is started (at
commissioning). T he lo west temperature ram p r at e will also be used if machine power has
been off for 3 hours or more ( ev e n if the motor ramp load is sele cted).
2. Motor load ramp loading limits the rate at which the compressor motor current or
compressor motor load increases by an operator-configured rate.
The
TEMP (Temperature) PULLDOWN, LOAD PULL DOWN,
and
SELECT RAMP TYPE
may be viewed/modifie d on the LID Equipment Conf ig uration table, Config t able (see Table 2).
Motor load is the default type.
Capacity Override (See Table 4)
These can preven t some safety shutdowns caused by exceeding mo tor amperage limi t,
refrigerant low temp erature safety limit, mot or high temperature saf ety limit, and condenser hig h
pressure limit. In all cases there are 2 stages of compressor vane control.
1. The vanes are held from ope ning further, and the status line on the LID indic ates the reason
for the override.
2. The vanes are closed un ti l condition decreases bel ow the first step set point , and then the
vanes are released to normal capacity control.