Detecting Current Errors; Heater Burnout Alarm (Hb Alarm) - Omron EJ1G User Manual

Detecting Current Errors

5-5

Detecting Current Errors

5-5-1

Heater Burnout Alarm (HB Alarm)

Note
88
A heater burnout is detected by measuring the heater current while the control
output (heating) is ON. For details, refer to the following table. (Heater burnout
detection cannot be used with the control output for cooling.)
Control output (heating)
ON
ON time
(See note 2.)
ON
Control output (heating)
OFF
(1) In the above diagram, power is considered to be ON (normal) if the heater
current is greater than the heater burnout detection current during the ON
time. If the heater is burned out, the current measured at the current
transformer decreases. When the current falls below the channel's Heat-
er Burnout Detection Value, a heater burnout alarm (HB Alarm) will be
output.
(2) Heater burnouts are not detected if the control output (heating) ON time
is 100 ms or less. Detection is also sometimes not possible if a contactor
is used for the control output.
Variable type
D6/96 (See note 3.) Heater Burnout 1 or 2
Detection
E4/A4 (See note 4.) Heater Burnout 1 or 2 Hys-
teresis
C5/85 Heater Current Value 1 or 2
Monitor
Conditions for use There must be a CT input.
(3) The HB Alarm can be forced OFF or ON, regardless of the actual heater
current value, by setting the Heater Burnout Detection parameter to 0.0
or 100.0. Use the 0.0 and 100.0 settings to check operation.
(4) The hysteresis setting prevents chattering at the detection point.
Set this parameter in the TC2/4 Unit.
• Turn the heater ON before the EJ1G, or turn both ON simultaneously. If
the heater power is turned ON after turning ON the EJ1G, the HB Alarm
will be output.
• Control will be continued even when there is an HB Alarm.
• The rated current value may sometimes differ slightly from the actual cur-
rent flowing to the heater. Check the current value in an actual operating
state in the Heater Current Monitor Value 1 or 2 parameter.
Power to heater
Yes (Normal) (See note 1.)
No (Heater burnout)
OFF time
Parameter name
0.0: HB Alarm OFF
(Channel) 0.1 to 99.9 A
100.0: HB Alarm ON
0.1 to 100.0 A
(I/O)
0.0 to 110.0 A
(Channel)
Section 5-5
HB Alarm output
OFF
ON
Setting range Default
0.0
0.1
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