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D33351-RTL 120/520 Eng.
24.06.15 AM
We reserve the right to make changes without notice
9. COMMUNICATION BUS P-LOC & POWER SUPPLY
These matters are dealt with fully in technical specification regarding the Master of the “MULTIZONE” MRL 608
system.
10. GENERAL FUNCTIONS
All the functions ofi RTL 120 and RTL 520 are exactly the same; the two devices differ only in regard to mechanical
aspects and to the way they are installed.
11. TEMPERATURE CONTROL
The unit is essentially a room temperature controller which can function in several different ways, and with several
different configurations, in order to best adapt to the ambient conditions it must control.
All the controller's main configuration parameters are set via the Master, which then sends them to the controller.
11.
1
Basic control to create the Controller Output
The system comprises a basic algorithm for ambient control which is the same in each configuration.
This basic controller essentially calculates, without interruption, the CONTROLLER OUTPUT, i.e. the POWER (hot
or cold), which the thermal unit (radiator, fan-coil or similar) has to deliver.
The basic controller may function in the following modes:
– PROPOR INTEGRAL
– PROPORTIONAL ONLY
– INTEGRAL ONLY
Choice of the correct option depends on the difficulties the controller may face in operating correctly.
The PROPOR INTEGRAL mode is usually the best suited.
The PROPORTIONAL BAND and/or Integral Time are parameters which require setting.
The factory (DEFAULT) settings are usually satisfactory.
These parameters are set independently for heating and conditioning control.
CONTROLLER OUTPUT (power required) results from the base controller's calculations.
CONTROLLER OUTPUT may be processed in various ways to adapt to the thermal unit.
The base controller is also provided with a neutral zone (adjustable from 0 to 3°C) as an acceptable room tempe-
rature tolerance range within which the thermal unit is not adjusted, in order to avoid too many interventions.
11.
2
Control of the output relay
The output relay may be controlled in two modes:
– PURE ON/OFF = the output relay is switched ON when the thermal unit must be switched on and vice versa.
– PROPORTIONAL ON/OFF= the output relay is controlled cyclically with a programmable cycle duration.
This is a more sophisticated way of controlling the thermal unit in order to limit thermal excursions.
Factory setting: the output relay is set to PURE ON/OFF (the simplest mode).
11.
3
0...10 Volt output proportional to REQUIRED POWER (CONTROLLER).
This output is necessary when the thermal unit to control has a 0...10 Volt input to pilot power issued.
For instance:
– FAN-COIL VENTILATOR SPEED CONTROL
– SMALL AIR-TREATMENT UNIT VENTILATOR SPEED CONTROL
– VARIABLE SPEED PUMP SPEED CONTROL
– BOILER POWER OR TEMPERATURE CONTROL
– ANY THERMAL UNIT WITH A 0...10 Volt INPUT
This output is proportional to the controller and therefore to the power required of the system at any specific time.
A minimum and maximum voltage limit may be set for the output, for instance:
– to guarantee minimum ventilation even when no thermal power is required
– to limit the top speed or power to avoid inconvenient noise or draughts.
11.
4
Values of the CONTROLLER OUTPUT for ON/OFF of the relay controlled as PURE ON/OFF.
To better adapt to different circumstances, the threshold at which the output relay is switched ON and OFF may
be set:
– CONTROL VALUE to switch ON the relay = 90% of the power (factory setting).
– CONTRO VALUE to switch OFF the relay = 10% of the power (factory setting).
11.
5
Cycle time for ON/OFF of relay controlled as ON/OFF PROPORTIONAL.
The cycle time is adjustable: default = 300 seconds.
11.
6
Minimum ON and OFF times of output relay.
In whatever mode the output relay is controlled you can establish a minimum time for which it must remain ON and
a minimum time for which it must remain OFF.
This function is very useful to avoid overworking the thermal unit when, for example, it is a wall-mounted gas
boiler.
11.
7
Heating and conditioning.
Control is provided for both heating or for conditioning the room.
This control order is received by the Master which has several modes for deciding on the basis of the type of
installation and the use.