Heater Disconnection Detection Function - Mitsubishi Electric MELSEC iQ-R Series User Manual

1.27

Heater Disconnection Detection Function

When a transistor output is ON, this function checks whether a heater has been disconnected or not by using a heater current
process value (load current value detected by a current sensor (CT)). This function compares the heater current process
value and the heater disconnection alert current value. When the heater current process value becomes equal to or smaller
than the heater disconnection alert current value, the heater is regarded as disconnected. However, when the transistor
output ON time is one of the following values, no heater disconnection is detected. (CH1 Heater disconnection detection
(Un\G401, b12) remains OFF.)
• When the heater disconnection judgment mode is the normal mode: 500ms or shorter
• When the heater disconnection judgment mode is the high accuracy mode: 200ms or shorter
The following shows the timing when an alert is output.
• 500ms  n
n = Value set for "Heater disconnection/output OFF-time current error detection delay count" of "Loop disconnection detection
setting" in "Application Setting"
When the heater disconnection status lasts longer than the time described above, the following operations are executed.
• The HBA LED turns ON.
• 'CH1 Alert flag' (XC) turns ON.
• CH1 Heater disconnection detection (Un\G401, b12) is turned ON.
• CH Heater disconnection detection (alarm code: 088) is stored in 'Latest alarm code' (Un\G3). ( Page 145 When
the temperature process value (PV) is abnormal)
Supported modules
• R60TCTRT2TT2BW
• R60TCRT4BW
Setting method
Configure the setting by the following procedure:
[Navigation window]  [Parameter]  Target module  [CT setting]
1.
Set the current sensor (CT) to be used for "CT selection."
2.
When using a current sensor (CT) other than the products manufactured by U.R.D.Co., LTD., set "CT ratio setting."
3.
Set the channel to be assigned to CT in "CT input channel assignment setting."
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1.27 Heater Disconnection Detection Function