Application manual
Air quality multisensor and regulator EK-ES2-TP
Release 1.0 - Updated: 14/02/2020
Application Manual
© EKINEX S.p.A. - All rights reserved
Page 87
differential adjustment of the air conditioning system, the device disables the air conditioning system by
sending another message. In this way, there are two decision thresholds for activation and deactivation of the
ai conditioning system: he first being the desired temperature T
set
above which the device activates the system,
whereas the second is the value (T
set
- ΔT
hysteresis
) below which which the air conditioning system is deactivated.
In the ETS application program, two different parameters are available for the hysteresis value for heating and
cooling: the values usually differ depending on the system type and its inertia.
In the ETS application program, the default 2-point hysteresis control algorithm foresees inferior hysteresis for
heating and superior for cooling. If Heating and/or cooling type = floor radiant panels or ceiling radiant panels,
it is possible to selet the hysteresis position according to the described second mode, i.e. with superior
hysteresis for heating and inferior for cooling.
The desired temperature (T
set
) is generally different for each one of the 4 operating modes and for
heating/cooling modes. The different values are defined for the first time during ETS configuration and can be
modified later on. In order to optimize energy saving (for each extra degree of room temperature, outbound
dispersions and energy consumption go up 6%), it is possible to take advantage of the multifunctionality of the
domotic system, for example with:
•
Hour programming with automatic commutation of the operating mode by means of KNX supervisor;
•
Automatic commutation of the operating mode according to presence of people in the room;
•
Automatic commutation of the opeating mode according to window opening for air refreshment;
•
Circuit deativation when desired temperature is reached;
•
Flow temperature reduction in case of partial load.
9.2
Continuous Proportional-Integral control
The continuous proportional-integral (PI) controller is described by the following equation:
𝑐𝑜𝑛𝑡𝑟𝑜𝑙 𝑣𝑎𝑟𝑖𝑎𝑏𝑙𝑒(𝑡) = 𝐾𝑝 × 𝑒𝑟𝑟𝑜𝑟(𝑡) + 𝐾𝑖 × ∫ 𝑒𝑟𝑟𝑜𝑟(𝜏)𝑑𝜏
𝑡
0
whereby:
𝑒𝑟𝑟𝑜𝑟(𝑡) = (𝑆𝑒𝑡𝑝𝑜𝑖𝑛𝑡 − 𝑀𝑒𝑎𝑠𝑢𝑟𝑒𝑑 𝑡𝑒𝑚𝑝𝑒𝑟𝑎𝑡𝑢𝑟𝑒) 𝑖𝑛 ℎ𝑒𝑎𝑡𝑖𝑛𝑔
𝑒𝑟𝑟𝑜𝑟(𝑡) = (𝑀𝑒𝑎𝑠𝑢𝑟𝑒𝑑 𝑡𝑒𝑚𝑝𝑒𝑟𝑎𝑡𝑢𝑟𝑒 − 𝑆𝑒𝑡𝑝𝑜𝑖𝑛𝑡) 𝑖𝑛 𝑐𝑜𝑜𝑙𝑖𝑛𝑔
𝐾𝑝 = 𝑝𝑟𝑜𝑝𝑜𝑟𝑡𝑖𝑜𝑛𝑎𝑙 𝑐𝑜𝑛𝑠𝑡𝑎𝑛𝑡
𝐾𝑖 = 𝑖𝑛𝑡𝑔𝑟𝑎𝑙 𝑐𝑜𝑛𝑠𝑡𝑎𝑛𝑡
The control variable is composed by 2 numbers, one depending proportionally from the error and one
depending from the integral of the error itself.
Practically, some more intuitive values are used:
𝑃𝑟𝑜𝑝𝑜𝑟𝑡𝑖𝑜𝑛𝑎𝑙 𝐵𝑎𝑛𝑑 𝐵𝑃 [𝐾] =
100
𝐾𝑝
𝐼𝑛𝑡𝑒𝑔𝑟𝑎𝑙 𝑇𝑖𝑚𝑒 𝑇𝑖 [𝑚𝑖𝑛] =
𝐾𝑝
𝐾𝑖
The Proportional Band is the error value that determines the maximum span of the control variable at 100%.
For example, a controller with Proportional Band = 5 K regulates at 100% when Setpoint = 20°C and Measured Temperature is ≤
15 °C in heating mode; in cooling mode, it regulates at 100% when Setpoint = 24°C and Measured Temperature is ≥ 29°C. As shown
in Picture 14, a controller with a narrow Proportional Band provides higher control variable values for smaller errors compared to a
controller with a wider Proportional Band.
