Technical Manual
Glass Room Temperature Controller Smart SCN-RTRGx.02
MDT technologies GmbH •
51766 Engelskirchen • Papiermühle 1
•
Germany
Phone: +49-2263-
880 • [email protected] • www.mdt.de
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PI control is a continuous control with a proportional component, the “P component” and an
integral component, the “I component”. The size of the P component is specified in K (Kelvin).
The I component is referred to as reset time and is specified in min (minutes).
The control value for continuous PI control is controlled in steps from 0% up to the set maximum
value of the control value.
Maximum value of control value
With this setting, the control value to be output can be limited. To prevent switching operations
with too high control values, the parameter can be set to a fixed value so that the actuator does not
exceed this maximum value.
Heating/ Cooling system
The individual control parameters, P-component and I-component are set by adjusting the
heating/cooling system used. It is possible to use preset values which are suitable for certain
heating or cooling systems or to freely parameterize the P-controller and I-controller components.
The preset values for the respective heating or cooling system are based on empirical values
proven in practice and usually lead to good control results.
If a free "
adjustment via control parameters
" is selected, the proportional band and reset time
can be freely set.
Important
: This setting requires sufficient knowledge in the field of control engineering
!
Proportional range
The proportional band stands for the P-component of a control. The P-component of a control
system leads to a proportional increase of the control value to the system deviation.
A small proportional band leads to a fast correction of the system deviation. With a small
proportional band, the controller reacts almost abruptly and sets the control value almost to the
maximum value (100%) even with small control differences. However, if the proportional band is
selected too small, the risk of overshooting is very high.
A proportional band of 4K sets the control value to 100% with a control deviation (difference
between setpoint and current temperature) of 4°C. Thus, with this setting, a control deviation of
1°C would result in a control value of 25%.
Reset time
The reset time represents the I-component of a regulation. The I-component of a regulation leads
to an integral approximation of the process value to the setpoint. A short reset time means that the
controller has a large I-component.
A small reset time causes the control value to quickly approach the control value set according to
the proportional band. A large reset time, on the other hand, causes the output variable to approach
this value slowly.
When making the setting, please note that a reset time that is set too small could cause
overshooting. In principle, the larger the reset time, the slower the system.
Send control value cyclically
With the aid of the parameter "Send control value cyclically" it can be set whether the channel
should send its current status at certain intervals. The time intervals between two transmissions
can also be parameterised.
