Carrier 19XL - Manual (Page 82)

Ramp Loading Control
The ramp loading control slows down the rate at which the compressor loads up. This control
can prevent the compressor from loading up during the short period of time when the machine
is started, and the chilled water loop has to be brought down to normal design conditions. This
helps reduce electrical demand charges by slowly bringing the chilled water to control point.
However, the total power draw during this period remains almost unchanged.
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 Table 2 ).
Motor load is the default type.