Omron E5EK, User Manual

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4.9 How to Use the Heater Burnout Alarm
E5EK
4--23
4.9 How to Use the Heater Burnout Alarm
•
On a standard type controller, the HBA (heater burnout alarm) func-
tion can be used only when the assignment destination of the output
function “control output (heat)” is set to pulsed output.
•
When using the HBA function, assign output function “heater burn-
out alarm” to control outputs 1/2 or auxiliary outputs 1/2.
•
Heater burnout detection works as follows:
(1) Connect the current transformer (CT) to terminal Nos.15 and 17,
and insert the heater lead through the CT hole.
(2) When current flows through this lead, the current transformer gen-
erates AC current proportional to the current value. The E5EK-T
measures this AC current to calculate the current flowing to the
heater.
(3) If the heater is burned out, the current measured at the current
transformer decreases. This value is compared with the value set as
the heater burnout set value and is output as the heater burnout
alarm.
•
Set the heater burnout set value in the “heater burnout alarm” pa-
rameter. To verify the current value of the current transformer, use
the “heater current monitor” parameter.
•
When you are not using the HBA function, set the “heater burnout
alarm” parameter to “0.0 (disabled)”.
•
When the HBA latch function is set to “ON”, the heater burnout
alarm is held until either of the following measures is taken:
a Set the heater burnout set value to “0.0A” (default).
b Reset the controller.
(Turn the controller’s power OFF then back ON again.)
•
To enable the HBA latch function, set the “HBA latch” parameter to
“ON”.
•
Turn the heater power supply ON at the same time as or before turn-
ing the E5EK-T power supply ON. If the heater power supply is
turned ON after turning the E5EK-T power supply ON, the heater
burnout alarm is output.
•
Control is continued even when the heater burnout alarm is output.
(That is, the controller attempts to control the heater as if the heater
burnout alarm has not occurred.)
•
The heater burnout alarm is detected only if the control output is
continuously ON for 190 ms minimum.
•
The rated current value may sometimes differ slightly from the actual
current value flowing to the heater. Verify the current value in an ac-
tual operating state in the “heater current monitor” parameter.
•
If there is little difference between the current in a normal state and
the current in a burnout state, detection may become unstable. On a
heater of current 10.0 A or less, maintain a difference of 1.0 A mini-
mum. On a heater of current 10.0 A minimum, maintain a difference
of 2.5 A minimum.
J
Heater burnout
detection
To E5EK-T
CT terminal
Heater wire
CT
F
HBA
latch/release
J
Operating
conditions