ECKELMANN Case Controller UA 4 E Series, Инструкция по эксплуатации

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Firmware V3.13 21.04.2021 51/466
5.7.7 Superheat control
Superheat control works parallel with temperature control. As required, control is made to the defined
superheatsetpoint. Superheat control works in two modes that can be toggled by a parameter (offset).
Operating mode “Stand Alone”: With activated local pressure transmitter (see chapter On-off control ):
Calculating differences in the temperature measured at the local pressure transmitter (suction gas
temperature, based on the measured pressure with the assistance of the set coolant table) and the temperature
measured at the evaporator output (R6.x). If the pressure transmitter fails, then in the first step an attempt is
made to switch to the operating mode “Interconnected Operation”. If this is not possible, for example because
“Interconnected Operation” is not configured or because the pack controller does not provide any suction
pressure, then an attempt is made to switch to stand alone operation with temperature sensors.
Operating mode “Stand Alone”: With evaporator inlet sensor Offset = --
Difference between temperature measured at evaporator inlet (R5.x) and evaporator outlet (R6.x). If it is
not possible to calculate the difference, for example because one of the two requisite temperature sensors does
not supply a value, then the system is switched to emergency operation.
Operating mode “Compressor pack”: Offset >= 0 K
Difference between evaporating temperature measured on compressor pack (transmitted via CAN bus) and
at evaporator outlet (R6.x). An adjustable offset corrects the temperature t0 measured by the pack controller
(suction pressure actual value) by any pressure loss in the suction line and the associated variations between
evaporating temperature on the suction pressure side and evaporator side. Correct transmission of suction
pressure via the CAN bus requires the Pack No. (menu 6-1) to be set on the case controller. When using a VS
3010 BS pack controller, the compressor pack parameter must also be set. If transmission of evaporating
pressure by the pack controller is interrupted, superheat is derived from the temperature difference between
R5.x and R6.x. As a supplementary protective function the expansion valve is fully closed if superheat
temperature drops below a critical minimum level.
Reset of the I-sum
The I-sum is reset in the case of the following events: During the defrost, manual shutdown, setpoint switching,
emergency operation and forced cooling. When the Reset I-Sum parameter (Menu 6-2-7) is set to ON, the
procedure is as follows:
If the valve opening is set to 0% due to superheat dropping below the low level, the I-sum integrated over
time (NOT the I-term) is additionally set to zero on the PID controller. This is applicable to both superheat
control and temperature control. Distinction also made by control zone.
This is intended to allow the controller to re-learn an I-sum that may have become too large, thus enabling it
to adjust to changed ambient conditions. When the Reset I-Sum parameter (Menu 6-2-7) is set to OFF, the
integrated I-sum is not changed on drop of superheat below the low level.
Analysis of the pack controller superheat
If the case controller is operated with a VS 3010 pack controller (version ≥ V3.00), then the superheat status
is also analysed.
If the superheat of the pack controller is in a non-critical range (dependent on the parameterisation of the
pack controller), then the case controller continues controlling even when there is a shortfall relative to the
minimum value of its own superheat. The case controller only closes the solenoid valve when the pack
controller superheat is also too low.