Carrier 17/19EX - Manual (Page 82)

alert threshold (18 psid [124 kPa]). Once running, the auxiliary oil pump will remain on until the
compressor is turned off and will deenergize with the main oil pump after the post-lube time
period.
Shaft Seal Oil Control (Open Drive Machines Only)
All open drive machines require that the shaft seal be bathed in oil at all times, especially
when the machine is not running. This ensures that refrigerant does not leak past the seal. The
PIC control will energize the oil pump for one minute if the oil pump has not operated during the
past 12 hours.
It is important to note that if control power is to be turned off for longer than this period, the
refrigerant charge must be pumped over into the utility vessel. Because the oil heater will also
be off during this time, storing the refrigerant will also prevent refrigerant migration into the oil.
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.