Load Shedding Failsafe Mode; Miscellaneous Page - nvent RAYCHEM Elexant 4010i User Manual

RAYCHEM-AR-H60624-40X0iOpsManual-EN-1905
Options:
A controller can be assigned up to 8 different load shedding zones.
Procedure:
The broadcast sent from the Modbus Master specifies which of these zones are to be load shed.
If the controller is a member of a zone specified for load shedding, it will turn its output off. After this
command has been received, the controller will continue to hold the output in the off state, until one of
the following three conditions occur:
1. The Modbus Master that initiated load shedding issues a load shedding command to terminate load
shedding mode.
2. Communications are interrupted between the controller and the Modbus Master, as in the case of a
damaged communications wire. If the communication ceases for a specified Timeout value
(60s to 600s), the controller will return to normal operation.
3. Failsafe operation begins. See Section 5.6.6 for details on Load Shedding Failsafe Operation.
5.6.6

Load Shedding Failsafe Mode

Purpose:
Load Shedding Failsafe mode is used to protect the EHT circuit from freezing if the control output is off
due to a load shedding command issued by the Modbus Master. Once the temperature of the TS used in
the TS CONTROL MODE drops to that sensor's LOW TEMP ALARM setting, the control output will go ON
and use the Low Temp Alarm setting as the temporary control setpoint.
Procedure:
Touch the Failsafe check box to enable Load Shedding Failsafe.
If the Failsafe parameter is enabled, then at least one Low Temperature Sensor Alarm must be enabled.
If the alarm temperature exceeds the Control Setpoint Temperature, failsafe mode will be disabled. If the
control temperature drops below the Control Temperature Low Alarm Setpoint, the output will turn on.
IMPORTANT: The controller returns to normal operation if communications between
the Modbus Master and the controller is disrupted in any way. The controller does not
perform a periodic autocycle test while operating in load shedding mode.
Default: Disable
5.6.7

Miscellaneous Page

Purpose:
The Miscellaneous page contains many different settings that are described below.
Figure 81 - Miscellaneous Page
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