Carrier 17/19EX Manual De Usuario

There are 2 methods of ramp loading with the PIC. Ramp loading can be based on chilled

water temperature or on motor load.

1. Temperature ramp loading limits the rate at which either leaving chilled water or entering

chilled water temperature decreases by an operator-configured rate. The lowest

temperature ramp table will be used the first time the machine is started (at

commissioning). The lowest temperature ramp rate will also be used if machine power has

been off for 3 hours or more (even if the motor ramp load is selected).

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/modified on the LID Equipment Configuration table, Config table (see

Motor load is the default type.

Capacity Override (See

Table 4

These can prevent some safety shutdowns caused by exceeding motor amperage limit,

refrigerant low temperature safety limit, motor high temperature safety limit, and condenser high

pressure limit. In all cases there are 2 stages of compressor vane control.

1. The vanes are held from opening further, and the status line on the LID indicates the reason

for the override.

2. The vanes are closed until condition decreases below the first step set point, and then the

vanes are released to normal capacity control.