Heater Overcurrent Alarm (Oc Alarm) - Omron EJ1 User Manual

Detecting Current Errors
Note
Installing Current
Transformers (CT)
(HS Alarm)
Calculating the Heater
Short Detection
Current Value
4-5-4

Heater Overcurrent Alarm (OC Alarm)

Note
HS Alarm Latch and Latch Cancel
The HS alarm latch can be used to keep an HS alarm ON once it goes ON.
The latch can be released by executing an operation command (Reset Error
or Software Reset), cycling the power, or setting the HS Alarm parameter to
100.0 A. Refer to 6-4-11 Operation Commands for details on the operation
commands.
Variable type
E4/A4 HS Alarm 1 or 2 Latch
This parameter can be set only when operation is stopped.
For details, refer to Installing Current Transformers (CT) (HB Alarm) on
page 88.
For details, refer to Calculating the Heater Burnout Detection Current Value
on page 89.
A heater overcurrent is detected by measuring the heater current while the
control output (heating) is ON. For details, refer to the following table.
(Heater overcurrent detection cannot be used with the control output for cool-
ing.)
Control output (heating)
ON
ON time
(See note 2.)
ON
Control output (heating)
OFF
(1) In the above diagram, it is considered normal if the heater current is less
than the heater overcurrent detection current. When an excessive current
flows in the heater, the current will exceed the heater overcurrent detec-
tion value and a heater OC Alarm will be output.
(2) Heater overcurrents are not detected if the control output (heating) ON
time is 100 ms or less. Detection is also sometimes not possible if a con-
tactor is used for the control output.
Variable type Parameter name
D6/96 Heater Overcurrent 1 or
(See note 3.) 2 Detection
E4/A4 Heater Overcurrent 1 or
(See note 4.) 2 Hysteresis
C5/85 Heater Current Value 1 or
2 Monitor
Conditions for use There must be a CT input.
Parameter name
Power to heater
Normal (See note 1.)
Heater overcurrent occurred
OFF time
Setting/monitoring range Default
0.0: OC Alarm ON
(I/O) 0.1 to 99.9 A
100.0: OC Alarm OFF
0.1 to 100.0 A
(I/O)
0.0 to 110.0 A
(I/O)
Section 4-5
Setting range Default
(I/O) 0: Disabled 0
1: Enabled
OC alarm output
OFF
ON
100.0
0.1
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