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4 Basic Operation
ON
Control output (heating)
OFF
In the above diagram, power is considered to be ON (normal) if the heater current is greater than
hb1 (Heater Burnout Detection Current) during the Ton interval. The HB alarm will be OFF in this
case. If the heater current is less than hb1 (Heater Burnout Detection Current) during the Ton
interval, the HB alarm will turn ON. Heater burnout is not detected if the ON time (Ton) for the
control output for heating is 100 ms or less (30 ms or less if the control period is 0.1 or 0.2 s).
Heater burnouts are not detected in the following cases.
• Turn ON the heater power supply simultaneously or before turning ON the E5@D power supply. If
the heater power supply is turned ON after turning ON the E5@D power supply, the HB alarm will
be output.
• Control will be continued even when there is an HB alarm.
• The rated current may sometimes differ slightly from the actual current flowing to the heater.
Check the current value in an actual operating state in the Heater Current Value 1 Monitor
parameter.
• If there is little difference between the current in normal and abnormal states, detection may be
unstable. To stabilize detection, set a current difference of at least 1.0 A for heaters lower than
10.0 A, and at least 2.5 A for heaters of 10.0 A or higher. If the heater current is too low, loop the
load line several times through a CT, as shown in the following diagram. Looping it through once
will double the detected current.
Load line
Precautions for Correct Use
Due to UL Listing requirements, use the E54-CT1L or E54-CT3L Current Transformer with the
factory wiring (internal wiring). Use a UL category XOBA or XOBA7 current transformer that is
UL Listed for field wiring (external wiring) and not the factory wiring (internal wiring).
Operating Procedure
Set the HB ON/OFF parameter in the Advanced Function Setting Level,
and set the Heater Burnout Detection 1 parameter in the Adjustment
Level.
Heater Burnout Detection 1 = 2.5
Operating Procedure
• Checking the HB ON/OFF Parameter Setting
1
Press the M Key several times in the Advanced Function
Setting Level to display hbu (HB ON/OFF).
4 - 40
Ton
Toff
Heater Burnout Detection 1/2 set value =
CT
(Normal current value + Burnout current value) × Number of turns
2
Advanced Function Setting
Level
hbu
E5@D Digital Temperature Controllers User's Manual (H224)
HB ON/OFF
on
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