Danfoss EKE 1A User Manual page 54

Superheat controller and stepper valve driver, Type EKE 1A, 1B, 1C, 1D
Fail Safe Operation
In the case of sensor error, the EEV controller will go into an emergency mode ("safe mode"). where the valve
opening degree is de ned by desired OD scheme as described below
User can read the failure status via [U118 Operation status].
EKE 1x implements two Failsafe mode:
• SH control Failsafe mode
• Thermostat Failsafe mode
Table 44: SH control Failsafe mode
SH control Failsafe mode:
SH control needs Pe and S2 signal. so, if one of these
signal fails, SH control based on the actual superheat
is not possible.
Table 45: SH control Failsafe mode parameters
Parameter
N143
N145 [only if N143= 1]
N138 [only if N144= 2]
Table 46: Thermostat Failsafe mode
Thermostat Failsafe mode
Thermostat sensor error.
Thermostat operation needs the signal selected in [R015 Sensor select] to oper-
ate the thermostat function, if this signal fails operation based on actual tempera-
ture is not possible
Table 47: Thermostat Failsafe mode parameters
Parameter Function
N144 Thermostat sensor error action
N145 [only if N144= 1] Fixed OD during emergency cooling
N138 [only if N144= 2] Average OD
Superheat close
SH close ensures that superheat is on or above 'SH close set point to avoid liquid getting back to the compressor. If
the media inlet temperature drops or if compressor goes down in capacity, the superheat may drop below the SH
close setpoint, then the ow in the expansion valve is reduced to bring superheat up to SH close setpoint as shown
in the gure below.
© Danfoss | Climate Solutions | 2024.08
Description
User can via parameter [N143] SH control sensor error action, under control advanced. con gure the relevant
option
valve forced closed and SH control (default)
Stop
valve at xed position (Fail safe OD), this keeps the refrigeration unit running
Fixed OD
Use average OD (calculated as an average of the last hour) to set a reduced OD which will be xed dur-
ing error period. This keeps the refrigeration unit running
Function
SH control sensor error
Fixed OD during
emergency cooling
Average OD
Description
0 = Stop | 1 = Fixed OD | 2 = Average OD
de ne xed OD % during Emergency cooling
Calculated When superheat control/ Temperature control is active and stored in
EEPROM. Its value is updated every 3 hours. Reset to factory will not delete the
calculated average values. Used in average OD
Description
User can via parameter [N144] Thermostat sensor error action] con gure the rel-
evant option.
valve forced closed, SH control and Temperature control (default)
Stop
valve at xed position (Fail safe OD). This Keeps the refrigeration
Fixed OD
running
Cutin /cutout use average on and o time to continue cool-
Use Average OD
ing
MTR use reduced OD based average OD (70% of average
OD).
Description
0 = Stop | 1 = Fixed OD | 2 = Average OD
De ne xed OD % during Emergency cooling
Calculated When superheat control/ Temperature control is ac-
tive and stored in EEPROM. Its value is updated every 3 hours.
Reset to factory will not delete the calculated average values.
Used in average OD
BC398828796060en-000103 | 54