Relays signal Alarm Levels 1 and 2
In RTD-10 Duty/Standby mode relay outputs R1 and R2 are configured to operate respectively as Level 1 and Level 2 alarm outputs, as opposed to RUN and Fault signals in RTD-10 Standard operation mode.
When is an alarm signalled?
Level 1 and 2 alarms occur when:
- Level 1 (Output relay R1):
- Unit Return Air > Setpoint + 2°C
- Aux. Space Temperature > Setpoint + 2°C
- A/C Unit Louvre Fault (A7)
- Alarm Level 2 Exists
- Level 2 (Output relay R2):
- Unit Return Air > Setpoint + 4°C
- Aux. Space Temperature > Setpoint + 4°C
- A/C Unit Fault (except A7)
- A/C Unit Missing (U5 Fault)
- RTD-10 Slave Missing (master RTD-10)
- RTD-10 No slaves found (master RTD-10)
- RTD-10 Master not found (slave RTD-10)
Note that any unit fault other than code A7 will result in a Level 2 alarm being generated. An A7 (louvre fault) will generate a Level 1 alarm.
The RTD-10 master will monitor all of the RTD slave devices discovered after power-up. If any of the RTD slave devices fail to respond the RTD-10 will raise a Level 2 alarm after 1 to 2 minutes.
If an auxiliary sensor (see this article for details) is fitted then the unit return air temperatures are not used for alarm generation. The Auxiliary sensor will raise alarms even if the units are overridden off (input S6 - see installation instructions).
If RTD-RA interfaces are added to and operated in the Duty/Standby network then any fault will be relayed to the master RTD-10 as described above as well (RTD-RA interfaces do not have output relays).
Which RTD signals which alarm?
- Master RTD-10:
- Relay outputs R1 and R2 on the Master RTD-10 operate respectively as Level 1 and Level 2 alarm outputs. The master's relays signal an alarm if a level 1 or level 2 alarm occurs on any RTD-10 (master or any slave).
- If a Level 2 alarm occurs then both R1 and R2 will be closed.
- Slave RTD-10:
- Slave output relays indicate the Alarm Level for that slave only.
What else happens when an alarm occurs?
All units will run if a Level 1 or Level 2 alarm occurs, except for an A7 (louvre fault) which will not force units on.
- If a Level 1 or Level 2 alarm occurs due to a unit or communications fault then all units will run until all faults are cleared.
- For correct Duty/Standby operation it is important that the Duty/Standby communication between Master and slave has been established for a first time. Any interruption of the Duty/Standby communication thereafter will result in the behaviour described above. Hence, if the slave looses communication to the Master both will switch On the respective units.
- If a Level 1 or Level 2 alarm occurs due to a high temperature on an indoor unit or the Auxiliary Space sensor then all units will run until temperature has reset and will continue to run on for 20 minutes before reverting to normal Run/Standby operation. In Test Mode (rotation = 60s) the run on time will be 40 seconds.
- If a Level 2 alarm occurs due to an Indoor Unit Fault then all units will run until the Indoor Unit Fault has cleared and will continue to run on for 10 minutes before reverting to normal Run/Standby operation. In Test Mode (rotation = 60s) the run on time will be 20 seconds.
- For RTD-RA interfaces which are added to and operated in the Duty/Standby network:
- If communications with the master is interrupted, after 120 seconds the RTD-RA will operate the A/C unit in COOL with 21C setpoint.