System information

ManualsBrandsAccel ManualsComputer equipmentAV316

Table 11 — Pre-Start Alerts and Alarms

*Evap trip point = 33 F (0.6 C) (water) or EVAP REFRIG TRIPPOINT

(brine).

The compressor RUN STATUS parameter on the default

screen line now reads PRESTART. If a test is not successful,

the start-up is delayed or aborted. If the tests are successful, the

chilled water pump relay energizes, and the main screen line

now reads STARTUP.

START-UP — One second after the successful pre-start check,

the chilled water and condenser water pump relays are ener-

gized.

Five seconds later, the control monitors the chilled water

and condenser water flow devices and waits until the WATER

FLOW VERIFY TIME (service-configured, default 5 minutes)

expires to confirm water flow.

After water flow is verified, the water temperature is com-

pared to CONTROL POINT +

CHILLED WATER DEAD-

BAND. If the temperature is less than or equal to this value, the

control turns off the condenser pump relay and goes into RE-

CYCLE mode.

If the RECYCLE condition does not exist, the start-up se-

quence continues and checks the guide vane position. For a sin-

gle-stage compressor (Comp [Single = 0, Dual = 1] = 0 in

FACTORY configuration), if the guide vanes are more than

4% open, the start-up waits until the controller closes the vanes.

For a dual-stage compressor (Comp [Single = 0, Dual = 1] = 1

in FACTORY configuration), the guide vanes are opened to the

initial position specified with GV1 Closure at Startup in the

Option Configuration menu.

If an HGBP or economizer damper valve is equipped and

enabled, the control checks that the position of these valves is

fully closed.

If the vanes and valves position are verified and the oil

pump pressure is less than 4 psi (27.6 kPa), the oil pump relay

is energized.

The control then waits until the oil pressure (OIL PRESS

VERIFY TIME, operator-configured, default 40 seconds)

reaches a maximum of 18 psi (124 kPa). After oil pressure is

verified, the control waits 40 seconds for oil prelube, and the

compressor start relay energizes to start the compressor.

Chiller Shutdown Sequence — Chiller shutdown

begins if any of the following occurs:

• Local OFF button is pressed

• A recycle condition is present (see the previous section)

• The time schedule has gone into unoccupied mode

• The chiller protective limit has been reached and chiller

is in alarm

• The start/stop status (CHIL_S_S) is overridden to stop

from the network

If the chiller is normally shut down from running, a soft-

stop shutdown will be performed. The soft-stop feature closes

the guide vanes of the compressor automatically if a non-alarm

stop signal occurs before the compressor motor is deenergized.

Any time the compressor is directed to STOP (except in the

cases of a fault shutdown), the guide vanes are directed to close

and VFD will be commanded to minimum speed for a variable

speed compressor. The compressor shuts off when any of the

following is true:

• AVERAGE LINE CURRENT (%) drops below the

SOFT STOP AMPS THRESHOLD

• ACTUAL GUIDE VANE POSITION drops below 4%

• Four minutes have elapsed since the stop was initialized

When any of these conditions is true, the shutdown se-

quence stops the compressor by deactivating the compressor

start relay. The guide vanes are then commanded to the fully

closed position. The oil pump relay will be turned off after 60

seconds post-lube.

Finally, the chilled water/brine pump and condenser water

pump are shut down.

Oil Lubrication Control — As part of the pre-start

checks executed by the controls, the oil sump temp is com-

pared to the evaporator saturated refrigerant temperature. If the

oil temperature is less than 140 F (60 C) and less than evapora-

tor saturated refrigerant temperature plus 50° F (27.8° C), the

start-up will be delayed until either of these conditions is no

longer true. Once this temperature is confirmed, the start-up

continues.

The oil heater relay is energized whenever the chiller com-

pressor is off and the oil sump temperature is less than 140 F

(60 C) or the oil sump temperature is less than the evaporator

saturated refrigerant temperature plus 53° F (29.4° C). The oil

heater is turned off when either of the following conditions is

true:

• Oil sump temperature is more than 152 F (66.7 C)

• Oil sump temperature is more than 144° F (62.2 C) and

more than the evaporator saturated refrigerant tempera-

ture plus 55° F (30.6° C).

The oil heater is always off when the compressor is running.

The oil pump is also energized for 30 seconds after each 30

minutes of the oil heat relay being energized in order to stir the

oil for more evenly distributed heating.

Control Points

SET POINT — The set point can be configured at the Setpoint

menu (“USER” access level).

The set point is determined by the heat/cool mode, EWT

PRE-START ALERT

CONDITION

STATE

NO.

ALARM

ALERT

STARTS IN 12 HOURS >= 8 100 Alert

OIL SUMP TEMP <= 140 F (60 C) AND OIL

SUMP TEMP <= EVAP_SAT + 50 F (27.8 C)

101 Alert

CONDENSER PRESSURE >=

COND PRESS OVERRIDE – 20 psi

102 Alert

Number of recycle restart in the last 4 hours is

greater than 5

103 Alert

COMP BEARING TEMP >= COMP BEARING

ALERT– 10 F (5.5 C)

230 Alarm

COMP MOTOR WINDING TEMP >= MOTOR

TEMP OVERRIDE – 10 F (5.5 C)

231 Alarm

COMP DISCHARGE TEMP >= COMP DIS-

CHARGE ALERT– 10 F (5.5 C)

232 Alarm

EVAP_SAT < Evap trip point* +

EVAP OVERRIDE DELTA T

EVAP REFRIG LIQUID TEMP < Evap trip

point* + EVAP OVERRIDE DELTA T

233 Alarm

AVERAGE LINE VOLTAGE <=

UNDERVOLTAGE THRESHOLD

234 Alarm

AVERAGE LINE VOLTAGE >=

OVERVOLTAGE THRESHOLD

235 Alarm

Guide vane 1 has not been calibrated success-

fully

236 Alarm