ENGLISH
LEVEL PROBE
At Power-on, the doser detects the status of the level probe in the boiler and, if necessary (lack of water), it orders the filling phase by energising
the filling solenoid valve EVLIV and the PUMP until the correct level of water is restored in the boiler.
(Time-out contemplated in the programmable filling phase - see TECHNICAL LEVEL Programming)
NOTE: When the system is switched on, the level control and regulation are enabled after about 6 seconds.
Whenever the level probe in the boiler does not detect the presence of liquid for 3 seconds, the filling phase is activated by energising the filling
solenoid valve EVLIV and the PUMP. When the probe again detects the presence of water for 3 consecutive seconds, the filling phase is interrupted
by de-energising the filling solenoid valve EVLIV and the PUMP.
BOILER LEVEL KO
EVLIV + PUMP = ON
The filling phase does not influence the possibility of both making coffee or tea selections and their new programming. Only the intervention of the
Time-out associated with the filling phase inhibits the functionality of the keyboard and of the actuators.
At the first regulation of the water level in the boiler, the system waits for the level probe to be covered before activating the ON/OFF relay.
It is possible to vary the sensitivity of the level probes by means of a parameter in the TECHNICAL LEVEL Programming which offers the following
possibilities:
-> LOW sensitivity
-> MEDIUM sensitivity
-> HIGH sensitivity
CHARACTERISTICS
The heating control is enabled for dosing in IDLE-ON status and uses a temperature probe and a control for the low voltage resistance.
At the first regulation the heating is activate only AFTER the level has been reached in the boiler, to protect the resistance.
In all other cases the heating is active if necessary except when the minimum level probe is uncovered; in this condition, heating is blocked immediately.
REGULATING MODES
Control may be exerted in 2 modes.
WITH ON/OFF REGULATION WITH 2°C HYSTERESIS
Temperature regulation is realised with a hysteresis of 2°C. The resistance is controlled by the ON/OFF relay which is de-energised when the
programmed temperature T°SET is reached (see TECHNICAL LEVEL Programming) and it is re-energised when the temperature falls by 2°C. A
timed filter is also fitted to avoid vibrations on the threshold of intervention.
To activate this function it is necessary to set all the pid constants at 0 in the TECHNICAL PROGRAMMING (see specific paragraph).
WITH PID REGULATION (DEFAULT SETTING)
The temperature regulation is carried out following a proportional, integrative and derivative algorithm. (see TECHNICAL LEVEL Programming for
the setting of the parameters)
The heating control is enabled for dosing in IDLE-ON status and uses a temperature probe
and a RISCAF low voltage control for Triac or solid state relays with PID function.
The temperature regulation is carried out following an algorithm that uses 3 constants:
- proportional
(kp)
- integrative
(ki)
- derivative
(kd)
The three constants must be adapted to every type of coffee doser according to the power characteristics of the resistance, the dimensions
of the boiler, its heat loss, etc.
The "set point value or T°SET" is the temperature that the boiler must be at during normal operation.
- If the temperature swings excessively around the T°SET in the heating or holding phase, with peaks of value that do not diminish over time, it is
necessary to decrease the proportional constant: Kp
- If the temperature swings excessively around the T°SET in the holding phase, with a very long period of oscillation and with peaks of value that
do not diminish over time, it is necessary to decrease the proportional integrative constant: Ki
- If the temperature has an excessive oscillation and is often larger than the T°SET during the heating or holding phase, but it attenuates as time
passes, it is necessary to decrease the derivative constant: Kd
- If the temperature tends to be below the T°SET value during the heating phase, getting farther away from it, it is necessary to increase the
derivative constant: Kd
- If the temperature tends to be constantly below the T°SET value during the heating phase, it is necessary to increase the proportional constant:
PUMP
150kΩ
for example in the presence of a water softener
400KΩ
normal water
1MΩ
for example in the case of mountain water or of a sight glass
COFFEE BOILER HEATING
BOILER LEVEL OK
PID
57
EVLIV + PUMP = OFF
PUMP
T°SET