5 4 Cool Only Control
5 4 Cool Only Control
An ETR-8300 is used to control a refrigerator at a temperature below 0 °C. To
avoid the set point adjustment beyond the desired range, SP1L is set at
-10 °C and SP1H is set at 0 °C. The desired temperature is lower than the
ambient, a cooling action is required. Hence select DIRT for OUT1. Since
output 1 is used to drive a magnetic contactor, O1TY selects RELY. A small
temperature oscillation is tolerable, hence use ON-OFF control to reduce the
over-all cost. To achieve ON-OFF control, PB1 is set with zero and O1HY is
set at 0.1 °C.
An ETR-8300 is used to control a refrigerator at a temperature below 0 °C. To
avoid the set point adjustment beyond the desired range, SP1L is set at
-10 °C and SP1H is set at 0 °C. The desired temperature is lower than the
ambient, a cooling action is required. Hence select DIRT for OUT1. Since
output 1 is used to drive a magnetic contactor, O1TY selects RELY. A small
temperature oscillation is tolerable, hence use ON-OFF control to reduce the
over-all cost. To achieve ON-OFF control, PB1 is set with zero and O1HY is
set at 0.1 °C.
Setup Summary:
Setup Summary:
FUNC=BASC
IN1=PT.DN
IN1U= °C
DP1=1-DP
OUT1=DIRT
O1TY=RELY
SP1L=-10 °C
SP1H= 0 °C
FUNC=BASC
IN1=PT.DN
IN1U= °C
DP1=1-DP
OUT1=DIRT
O1TY=RELY
SP1L=-10 °C
SP1H= 0 °C
User Menu:
User Menu:
PB1=0 ( °C )
O1HY=0.1 ( °C )
PB1=0 ( °C )
O1HY=0.1 ( °C )
Cooling Control Example
Cooling Control Example
Figure 5.6
Figure 5.6
RTD
Refrigerator
18
19
20
3
4
Mains
Supply
Mains
Supply
87
ON-OFF control
Direct Control Action
ON-OFF control
Direct Control Action
ETR-8300
Out1 Out2
Alm1 Alm2
