FORM 155.21-O1 (615)
39
JOHNSON CONTROLS
Automatic Restart After Power Failure
Access Level required:
OPERATOR
This function defines how the unit will react to a power
failure. If the setpoint is enabled and the unit was run-
ning, it will attempt to restart automatically. If the
setpoint is disabled it will only restart upon a manual
request.
Enabled (Auto Restart):
When the unit recovers power and the strong solution
temperature is greater than crystallization limit tem-
perature and the unit was running prior to the power
failure: The unit is in a safe condition and restarts au-
tomatically.
Enabled (Auto Restart):
When the unit recovers the power and strong solution
temperature is less than crystallization limit temperature,
and the unit was running prior to the power failure: a
cycling shutdown occurs, unit will start a dilution cycle
and when it finishes (safe condition), the unit restarts
automatically.
Disabled (Manual Restart):
When the strong solution temperature is greater than
crystallization limit temperature and the unit was NOT
in ready to start, in finished dilution cycle (safe condi
-
tion), prior to power failure: Activates Safety Shutdown
and waits for a Manual Reset.
If the unit was in ready to start, manual dilution cycle,
in finished dilution cycle before the power failure, it
does NOT matter if the setpoint is enabled or disabled.
The unit is ready to start and shows message "POWER
FAILURE OCCURED".
If the strong solution temperature is less than or equal
to the crystallization limit temperature and the unit was
NOT in ready to start, in finished dilution cycle, prior to
the power failure, it does NOT matter if the setpoint is
enabled or disabled. Activates safety shutdown.
Purge Pump Service Interval
Access Level required:
OPERATOR
This setpoint warns the operator when the purge pump
needs service. There is a purge pump operation time
counter, and when it is greater than the preprogrammed
purge pump service interval setpoint value, a warning
appears in the control, this warning must be reset by the
operator to be erased.
RANGE: 5 Hours - 100 Hours
DEFAULT: 10 Hours
Maximum Purge / Week
Access Level required:
OPERATOR
This setpoint warns the operator regarding non condens-
able gases in the unit. When the automatic purge events
counter is greater than the maximum allowed purge per
week setpoint value, a warning appears in the control.
This warning must be reset by the operator to clear and
reset the counter.
Critical setpoint default value should
be used unless otherwise directed by
Service.
RANGE: 2 purges/week - 6 purges/week
DEFAULT: 4 purges/week
Purge Warm-up
Access Level required:
SERVICE
This setpoint defines how long the purge pump will
be operating to warm up the purge oil before purging.
When a purge process starts, the first step is to start the
purge pump for the indicated time in the purge warm-
up setpoint to heat the purge oil before opening the
valves to the chiller. The purge process initiates after
this setpoint time. If the warm up period is not enough
to achieve operating temperature, the purge pump may
have reduced ability to pull vacuum.
RANGE: 2 min. - 20 min.
DEFAULT: 2 min.
LCHLT Shutdown Offset
Access Level required:
OPERATOR
This setpoint defines how far the LCHLT can be under
the LCHLT setpoint before low LCHLT cycling shut
-
down occurs. The control activates a cycling shutdown
when the LCHLT less than or equal to LCHLT setpoint
- LCHLT Shutdown offset, and the unit recovers when
the LCHLT is greater than LCHLT se 2. This
setpoint is automatically overridden to NOT allow
LCHLT less than 38
°F (3.3°C). This value should be
set to match thermal inertia of the site to avoid short-
cycling the chiller.
RANGE: 2°F - 4°F (-16°C - -15.5°C)
DEFAULT: 3°F (-16.1°C)
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