Setup | Rtds Window - Pentair raychem ngc-30/uit2 Programming Manual

Fail safe toggle button
The Fail Safe control button turns the power on or off to the heater if the Circuit loses all valid RTDs.
When the last remaining sensor for control fails (or communication with the sensor is lost), the
NGC-UIT2:
• Signals an alarm for the failure of the sensor
• Changes control of the circuit to the fail safe control selected
• Changes the control status display to indicate that control of the circuit is in the fail safe state
• Records the events
When the sensor for control is returned to service, the controller signals the alarm has been
cleared, returns the Circuit to its normal control mode, and records both of these events.
imPortant: Default is OFF

3.3.5 setuP | rtds WindoW

In order to assign an RTD to a Circuit, it must be shown in the Network|Devices table.
By default, each NGC-20 controller and each channel of the NGC-30-CRM/-CRMS has an
associated RTD input.
The NGC-30 program first checks to see if the default RTD is available. On any NGC-30-CRM/-
CRMS (5GF-C) board, the first RTD input is automatically coupled with the first relay output; the
second RTD is linked with the second output relay, etc. When a control layout is chosen with an
RMC and RMM2 then, by default, no RTD will be associated with the RMC output channel. The
users decide themselves which temperature input is linked to which output channel.
Fig. 3.11 indicates an RTD connected to the RTD 1 terminal block, so the RTD set-up screen
indicates the default assignment is already completed. This selection is grayed out because you
cannot alter this default selection. In the event of a communications failure or UIT2 failure, the
circuit reverts to this default RTD for control purposes.
Fig. 3.10 Setup | RTDs window - Default RTD, hard-wired to CRM/-CRMS board
In general, up to three additional RTDs can be associated with this Circuit. When the system is
fully functional, the lowest RTD value from the list of four will be used for control temperature. If
no RTD is connected to the input terminals for this Circuit, then all four lines can be used to assign
RTDs from elsewhere in the system. However, in the event of a communications or UIT2 failure, no
industrial heat tracing solutions EN-RaychemNGC30UIT2Programming-AR-H58186 02/16 33 / 84