Alarm Parameter Module (4-AL) (Optional)
The controller may be equipped with one or two optional alarms. On some
models alarm output #1 is the same output as main control O1. In this case, the
output is either programmed for the main output control function (O1) or as an
alarm function (A1). This is set by alarm #1 action parameter (Act1).
If heat is selected, the remaining Alarm 1 parameters do not appear.
To enable the cooling output of the controller, select CooL for Alarm 2
action (Act2). The controller then utilizes the alarm 2 output as the cooling
output (O2). Front panel annunciator A2 illuminates whenever the cooling
output is on. See Cooling Output Module (5-O2), page 43, for configuration
of the cooling output.
If cooling is selected, the remaining Alarm 2 parameters do not appear.
Alarm Action (Act1, Act2)
Note: When deviation low-acting with positive alarm value (d-LO), deviation
high-acting with negative value (d-HI), or Band inside-acting (b-IN) is
selected for the alarm action, the indicator is “OFF” when the alarm output
is “ON”.
Caution: In applications where equipment or material damage, or risk
to personnel due to controller malfunction could occur, an
independent and redundant temperature limit indicator with alarm
outputs is strongly recommended. The indicators should have input
sensors and AC power feeds independent from the other equipment.
The configuration options of the alarm output are model dependent.
(Act1) - Alarm #1 (Act2) Alarm #2
A-HI Absolute High Acting A-HI Absolute High Acting
A-LO Absolute Low Acting A-LO Absolute Low Acting
d-HI Deviation High Acting d-HI Deviation High Acting
d-LO Deviation Low Acting d-LO Deviation Low Acting
b-In Band Inside Acting b-In Band Inside Acting
b-Ot Band Outside Acting b-Ot Band Outside Acting
Heat * Assigns output 01/A1
as control output
CooL * Assigns 02/A2 as cooling
or second output
Hcur * Assigns A1 as heater
break alarm (T48)
Hcur * Assigns A2 as heater
break alarm (T48)
* Model Number Dependent.
Note: Deviation and band type alarms track both local and remote setpoint.
Heater Break Alarm
T48 models equipped with the Heater Current Monitor provide an alarm
output in the event of a heater or a heater control circuit failure. The alarm is
dual mode and activates under either of the following two conditions:
1. Main control output (O1) is on for a minimumof 600 msec and the feedback
heater current is below the alarm value.
2. Main control output (O1) is off for a minimum of 600 msec and the
feedback heater current is above 10% +0.5 amp of the alarm value.
For heater ground faults, the heater power circuit fuse opens. The heater
break alarm activates per condition one above. This alarm is only useful for
controller output cycle times (CYCt) of 10 seconds or more, due to the
minimum on and off times of alarm detection.
The heater break alarm value is usually set in the range of 50% to 80% of
the nominal heater current. This usually provides sufficient margin against
false alarms that may occur from line voltage drops and normal heater aging.
Set the alarm value after observing the actual heater current readout.
If the alarm is set for latching operation, the controller delays alarm action an
additional 1 second (both on and off alarm detection). This suppresses false
alarm outputs in the event of a brief power glitch in the heater circuit. A latched
heater break alarm requires manual reset. If the alarm is set for auto reset
(non-latching), once past the 600 msec minimum dwell time the alarm triggers
and releases immediately after the condition that caused the alarm clears.
-39-
To Next Page
Loading...
