Carrier 17/19EX - Manual (Page 55)

6-Pack Relay Board
This device is a cluster of 6 pilot relays located in the control center. It is energized by the
PSIO for the oil pump, oil heater, alarm, optional hot gas bypass relay, and motor cooling
solenoid (19EX machines) on auxiliary oil pump (17EX machines).
8-Input Modules
One optional module is factory installed in the control center panel when ordered. There can
be up to 2 of these modules per chiller with 8 spare inputs each. They are used whenever
chilled water reset, demand reset, or reading a spare sensor is required. The sensors or 4 to
20 mA signals are field-installed.
The spare temperature sensors must have the same temperature/resistance curve as the
other temperature sensors on this unit. These sensors are rated 5,000 ohm at 75 F (25 C).
Oil Heater Contactor (1C)
This contactor is located in the power panel and operates the heater at 115 v. It is controlled
by the PIC to maintain oil temperature during machine shutdown.
Oil Pump Contactor (2C)
This contactor is located in the power panel. It operates all 200 to 575-v oil pumps. The PIC
energizes the contactor to turn on the oil pump as necessary.