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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 un-

changed.

There are 2 methods of ramp loading with the PIC. Ramp

loading can be based on chilled water temperature or on mo-

tor load.

1. Temperature ramp loading limits the rate at which either

leaving chilled water or entering chilled water tempera-

ture decreases by an operator-conﬁgured rate.

2. Motor load ramp loading limits the rate at which the com-

pressor motor current or compressor motor load in-

creases 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 selection

(see Table 3). Motor load is the default type.

Capacity Overrides (Table 5) — These can prevent

some safety shutdowns caused by exceeding motor amper-

age 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 slide valve

control.

1. The slide valve is held from closing further, and the sta-

tus line on the LID indicates the reason for the override.

2. The slide valve is opened until condition decreases be-

low the ﬁrst step set point, and then the valve is released

to normal capacity control.

Whenever the motor current demand limit set point is reached,

it activates a capacity override, again with a two-step pro-

cess. Exceeding 110% of the rated load amps for more than

10 seconds will initiate a safety shutdown.

Oil Sump Temperature Control (Frame 1 and 2

Machines Only) —

The oil sump temperature control

is regulated by the PIC using the oil heater relay when the

machine is shut down. The oil heater relay is energized when-

ever the chiller compressor is off, and the oil sump tempera-

ture is less than 140 F (60 C) or sump temperature is less

than the cooler refrigerant temperature plus 60 F

(33 C). The heater is then turned off when the oil sump tem-

perature is:

1. More than 160 F (71 C).

2. The sump temperature is more than 145 F (62.8 C) and

more than the cooler refrigerant temperature plus 65 F

(18.3 C). (The heater is always off during start-up or when

the compressor is running.)

NOTE: Frame 4 units do not use an oil heater.

All oil ﬁlter isolation valves should always be left open,

except when changing the oil or oil ﬁlter as deﬁned in

the Changing Oil and Oil Filter section, page 64.

Remote Start/Stop Controls — A remote device, such

as a timeclock, which uses a set of contacts, may be used to

start and stop the machine. However, the device should not

be programmed to start and stop the machine in excess of 2

or 3 times every 12 hours. If more than 8 starts in 12 hours

occur, then an ‘‘Excessive Recycle Starts’’alert is displayed,

preventing the machine from starting. The operator must re-

set the alert at the LID in order to override the starts counter

and start the machine. If Automatic Restart After a Power

Failure is not activated when a power failure occurs, and the

remote contact is closed, the machine will indicate an alarm

because of the loss of voltage.

The contacts for Remote Start are wired into the starter at

terminal strip TB5, as well as terminals 8A and 8B. See the

certiﬁed drawings for further details on contact ratings. The

contacts must be dry (no power).

Spare Safety Inputs — Normally closed digital in-

puts for additional ﬁeld-supplied safeties may be wired to

the spare protective limits input channel in place of the factory-

installed jumper. (Wire multiple inputs in series.) The open-

ing of any contact will result in a safety shutdown and LID

display showing ‘‘SPARE SAFETY DEVICE.’’

Analog temperature sensors may also be added to the op-

tions modules, if installed. These may be programmed to cause

an alert on the CCN network, but will not shut the machine

down.

SPARE ALARM CONTACTS — Two spare sets of alarm

contacts and provided within the starter. The contact ratings

are provided in the certiﬁed drawings. The contacts are lo-

cated on terminal strip TB6, as well as terminals 5A, 5B,

5C, and 5D.

Condenser Pump Control — The machine will moni-

tor the CONDENSER PRESSURE and may turn on this pump

if the pressure becomes too high whenever the compressor

is shut down. CONDENSER PRESSURE OVERRIDE is used

to determine this pressure point. This value is found on the

Equipment Service1 LID table and has a default value

(Table 3). If the CONDENSER PRESSURE is greater than

or equal to the CONDENSER PRESSURE OVERRIDE, and

the ENTERING CONDENSER WATER TEMP (Tempera-

ture) is less than 115 F (46 C), then the condenser pump will

energize to try to decrease the pressure. The pump will turn

off when the condenser pressure is less than the pressure over-

ride less 5 psi (34 kPa) [3.5 psi (24 kPa)], or the CON-

DENSER REFRIG (Refrigerant) TEMP is within 3° F (2° C)

of the ENTERING CONDENSER WATER temperature.

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