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267
CHAPTER 4 FUNCTIONS
4
4.28 Heater Disconnection Detection Function
Ex.
When CH Heater disconnection alert setting (Un\G58, Un\G90, Un\G122, Un\G154) is 80% and the
differences between CH Heater current and the reference heater current value are the following values:
• CH1: -16%
• CH2: -17%
• CH3: -22%
• CH4: -19%
The following table lists the result.
In the table above, the correction value is -16%. Heater disconnection is detected based on the
differences of 0% for CH1, -1% for CH2, -6% for CH3, and -3% for CH4. When Heater disconnection alert
setting is set to 80%, none of the channels are regarded as disconnected.
(b) Restrictions
• When only one channel is used, the heater disconnection compensation function does not work. To use
this function, two channels or more need to be used.
• When several channels are used with a heater on for one channel and heaters off for other channels, the
heater disconnection compensation function does not work. Therefore, disconnection may be detected
even if there is no disconnection.
• The heater disconnection alert correction value is 20% at maximum. When Heater disconnection alert
setting is set to 80% as shown in the two examples on Page 266, Section 4.28 (3) (a), the conditions
for disconnection detection are satisfied even if correction is performed by 20% with a voltage drop by
40% or more. Consequently, disconnection is detected.
(c) Setting method
Set Heater disconnection compensation function selection (Un\G170) to Use the heater disconnection
compensation function (1). ( Page 131, Section 3.4.2 (44))
Channel
CH Heater
disconnection alert
setting (Un\G58, Un\G90,
Un\G122, Un\G154)
Difference between
CH Heater current
and reference heater
current value
Correction
value
Difference between
CH Heater current and
reference heater current
value after correction
Disconnection
detected
CH1
80 (%)
-16%
-16%
0% (= -16% - (-16%)) Not detected
CH2 -17% -1% (= -17% - (-16%)) Not detected
CH3 -22% -6% (= -22% - (-16%)) Not detected
CH4 -19% -3% (= -19% - (-16%)) Not detected