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Definitions
ANALOG SIGNAL — An analog signal varies in propor-
tion to the monitored source. It quantifies values between
operating limits. (Example: A temperature sensor is an ana-
log device because its resistance changes in proportion to
the temperature, generating many values.)
DIGITALSIGNAL — A digital (discrete) signal is a 2-position
representation of the value of a monitored source.
(Example: A switch is a digital device because it only in-
dicates whether a value is above or below a set point or bound-
ary by generating an on/off, high/low, or open/closed signal.)
VOLATILE MEMORY — Volatile memory is memory in-
capable of being sustained if power is lost and subsequently
restored.
The memories of the PSIO and LID modules are vola-
tile. If the battery in a module is removed or damaged,
all programming will be lost.
General — The 17EX externally geared open-drive cen-
trifugal liquid chiller contains a microprocessor-based con-
trol center that monitors and controls all operations of the
chiller. The microprocessor control system matches the cool-
ing capacity of the chiller to the cooling load while provid-
ing state-of-the-art chiller protection. The system controls
cooling load within the set point plus the deadband by sens-
ing the leaving chilled water or brine temperature and regu-
lating the inlet guide vane via a mechanically linked actua-
tor motor. The guide vane is a variable flow prewhirl assembly
that controls the refrigeration effect in the cooler by regu-
lating the amount of refrigerant vapor flow into the com-
pressor. An increase in guide vane opening increases capac-
ity.Adecrease in guide vane opening decreases capacity. Chiller
protection is provided by the processor which monitors the
digital and analog inputs and executes capacity overrides or
safety shutdowns, if required.
1—Gear Mesh
2—Bearings
3—Gear Mesh Spray
4—Oil Level Glass
5—Orifice
6—Oil Supply Pressure
Transducer
7—Pressure Control Valve
8—Oil Supply Temperature Thermistor
9—Oil Pump Motor
10 — Oil Pump and Pressure Regulator
11 — Oil Filter
12 — Oil Cooler/Filter
13 — Oil Cooler
14 — Plug Valve
NOTE: The oil reservoir is at the base of the gear box.
Fig. 5 — External Gear Oil Lubrication Cycle (Plan View)
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