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Raychem-AR-H58692-ACS30UIT2Programming-EN-1805
USING RTDS WITH THE DIFFERENT APPLICATION CONTROL MODES
In certain modes, you have an option of choosing if the circuit is controlled by RTDs that are
measuring line (pipe, slab or surface) temperature, by RTDs that are measuring the ambient
temperature or by using dry contact relays from external moisture controllers (see Table 2.3 RTD
and External Control Functions on page 32 for more detail).
Line and Surface Temperature Control:
RTD assignment will be the same as described in the previous section.
Ambient or PASC Control:
RTDs must be assigned for either ambient control or line monitoring
Ambient Control
inputs will be used to turn the heating cable on or
off. RTDs in this mode will not trigger any temperature alarms.
Line Monitoring
with temperature alarms
Fig. 2.16 Ambient Control or Line Monitor
HWAT Mode:
No RTDs are required or can be used for control. However RTDs can be assigned for
line monitoring with temperature alarms.
External Device Control:
A controller may be used as external device control in roof & gutter and
snow melting applications or as an external override for other applications. The dry contact output
of the external device is connected to the RTD input on the ACS-PCM2-5 panel or RMM2. For the
C910-485 there are terminals to land the external device, not the RTD input. When the contact
is open the circuit is off and when closed the circuit is powered. Refer to Appendix 5.3 for wiring
instructions.
RTDs may be associated to the circuit for high temperature override. RTDs in this mode will not
trigger any temperature alarms.
External Device Override:
An external device or BMS system with dry contacts may be used to override the local RTD input to
force the circuit on or off. All programmed temperature alarms and high temperature cut out values
will still be active.
