Technical data

Instructions Manual cod. 1592001120
1592001121 Universal-R3 GB 19.11.2004.doc
rel. 1.0
Pa. 13 / 15
15. SPECIAL APPLICATIONS – TWIN COMPRESSOR – DEAD BAND CONTROL
16.1 TWIN COMPRESSOR
If the evaporator fan relay is not being used, the Universal-R can control a second compressor with this relay, using
parameter “FnC”. Parameter “Fnd” ( normally used for fan delay ) now becomes the delay between the starting of
compressor 1 and 2. Both compressors will stop simultaneously
FnC = 4 The evaporator fan relay is used to control the second compressor
Fnd = 0 to 250 (minutes) Time delay between the start of the 1
st
and 2
nd
compressors.
16.2 DEAD BAND CONTROL (cooling & heating)
With oAc = 1, the compressor relay controls cooling as normal but the 4
th
(auxiliary) relay is used to control a heater.
The value entered in parameter HY will now be set equal on both sides of the SET POINT. Example: if HY = 1
°
c that will
create a 2
°
c Dead Band
At SET POINT + HY, cooling switches on. At SET POINT – HY, heating switches on. Either cooling or heating switch off
when temperature returns to SET POINT
16. ALARMS
Message – Mode Cause Outputs
“EE” Flashing Data or memory failure Alarm output ON; Other outputs unchanged
“P1”Flashing Thermostat probe failure Alarm output ON; Compressor output according to
parameters “COn” and “COF”
“P2”
Alternating with room temperature
Evaporator probe failure Alarm output ON; Other outputs unchanged; End
defrost is timed
“HA”
Alternating with room temperature
High temperature alarm Alarm output ON; Other outputs unchanged.
“LA”
Alternating with room temperature
Minimum temperature alarm Alarm output ON; Other outputs unchanged.
“dA”
Alternating with room temperature
Door open alarm Alarm output ON: Outputs re-start if parameter rrd= 1
“EA”
Alternating with room temperature
Generic external alarm Alarm output ON; Other outputs unchanged.
“bAL”
Alternating with room temperature
Serious external alarm Alarm output ON; Other outputs OFF.
16.1 MUTING ALARM BUZZER & RELAY
The alarm buzzer can be muted, by pressing any button. The controller will briefly show the reset “rES” label. Parameter
tbA defines how the alarm relay will respond to the muting of the buzzer.
tbA = 0 The alarm relay will remain active until the alarm condition is rectified
tbA = 1 The alarm relay de-activates when the buzzer is muted
In either case, the display will flash an alarm label until the condition is rectified
16.2 ALARM “EE”
The Dixell Universal-R is provided with an internal watchdog verifying data and memory integrity. Alarm “EE” flashes
when a failure in data or in the internal memory is detected. In such case the alarm output is enabled.
WHAT TO DO
1. Cancel the alarm by pressing a key.
2. Check the value of all parameters and restore correct values when wrong.
3. Check the correct instrument operation and in case of further errors replace it.
16.3 ALARM RECOVERY
Probe alarms “P1” and “P2” start 30 seconds after a fault in probe is detected; they automatically stop 30 seconds after
the probe restarts normal operation. Check connections before replacing the probe.
Temperature alarms “HA” and “LA” automatically stop as soon as the thermostat temperature returns to normal values
and when defrost starts.