Omron Sysmac CJ Series, Operation Manual

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Using the Heater Burnout Alarm Section 3-11
wire. The current flowing through the heater can be determined from the
current induced in the CT.
3. The current will drop if there is a heater burnout and the heater burnout
alarm (HB output) will be turned ON if the current falls below the preset
heater burnout current.
4. The HB output is a latched output. To release the latch (i.e., turn OFF the
HB output), either set the heater burnout current to 0.0, turn the power OFF
and ON again, or restart the Temperature Control Unit.
Note 1. Do not use any CT other than the OMRON E54-CT1 or E54-CT3 Current
Transformer.
2. Set the desired heater burnout detection current in the Heater Burnout
Current word. The value in the Heater Current Monitor word can be used
to check the CT’s current.
3. Set the heater burnout current to 0.0 if you are not using the heater burnout
detection function.
4. The heater burnout current is set independently for each loop.
3-11-2 Operating Conditions
• Connect the CT and pass the heater wire through the CT in advance.
• Turn ON the heater’s power supply before the Temperature Control Unit or
turn ON both at the same time. The heater burnout alarm will be output if
the heater’s power supply is turned ON after the Temperature Control
Unit.
• Temperature control will continue even if a heater burnout is detected, so
that the Unit can continue controlling heaters that have not burned out.
• Heater burnout detection will operate when the control output has been
ON continuously for more than 200 ms.
• Sometimes the heater’s rated current does not match the current that
actually flows through the heater. Use the heater current monitor to check
the current during actual use.
• Heater burnout detection will be unstable if there is only a small difference
between the normal current and heater burnout current. For stable opera-
tion, set a minimum difference of 1.0 A with heaters drawing less than
10.0 A or a minimum difference of 2.5 A with heaters drawing more than
10.0 A
• The heater burnout detection function cannot be used if the heater is
being controlled with the position control method or cycle control method.
Also, the heater burnout detection function cannot be used with three-
phase heaters.
Note To detect heater burnout in a three-phase heater, use a K2CU-F @@ A- @ GS
(with gate input terminals). Refer to the catalog for more details.