Product Overview

© Danfoss | DCS | 2019.04
Data sheet | Superheat controller type EKE 1A, EKE 1B, EKE 1C
DKRCC.PD.RS0.A4.02 | 46
Danfoss 84B1487.10
100 %
10 %
40 %
Superheat
Q
o
Unstable region
(wet)
Stable
region (dry)
Min. SH Max. SH
Danfoss MSS
17.2 MSS The controller will search for the minimum stable superheat between an upper and lower boundry. If
the superheat has been stable for a period, the superheat reference is decreased.
If the superheat becomes unstable. the reference is raised again. This process continues as long as the
superheat is within the bounds set by the user. The purpose of this is to search for the lowest possible
superheat that can be obtained while still maintaining a stable system.
EKE 1A 1B 1C
Applicable
MSS PI controller is made up of 3 parts:
• a stability set point
• the variant from the Te signal
• actual superheat reference
The stability set point is given from the “user”. The variants from the T0 signal is used to allow for
increased instability if the T0 signal is unstable. Finally the part from the actual superheat allows for
more instability at higher superheat references than at lower references.
The superheat reference SH ref is adaptive and adjusted. When using this form of control, there are
three settings that have major eect on this mode of control. These are Min. SH, Max. SH and SH close
parameters.
Where to use:
MSS is a benet for system with a long runtime and slow changing conditions like cold rooms,
display cases and chillers.
Short cycling and system with fast changing operation condition will not benet from MSS as this
feature will take time to nd the optimal reference. Adaption to a new set point is approx. 15min.
Parameter Function Description
R102 Operation mode
0 = SH Control
N021 SH reference mode 2 = MSS
N009 SH max. value Max. allowed SH reference
N010 SH min. value
Min. allowed SH reference
Note: SH min. value must be >0.5K higher than SH close value, if N117=1
N018 Stability
Stability factor for regulation of superheat, only relevant for MSS.
With a higher value the control function will allow a greater uctuation of the
superheat before the reference is changed.
N129 T0 varians factor
Only relevant for MSS. Te variance factor denes if variation in suction
pressure will inuence superheat reference. The sh reference change
can be adjusted the value 0-1 (1= max Te inuence and S2, 0 = S2
only ). With often change in suction pressure due compressor start/
stop some Te (and S2)inunce on MSS is recommenend.
N117 SH close function
0 = O | 1 = On, default = 1
N119 SH close setpoint
default value =2 K (recommended)
Note:
for typical application. as a
rst step always start the MSS
with a start point of 4 K to 8 K
and SH close = 2 K.