high low limitation in temperature controller-

“Alarm Over-Temperature” VS “High Low Temperature” VS “Upper Lower Temperature”


 


Last updated on November 17th, 2022 at 02:28 pm

Alarm Over-Temperature

It is a span or range that exceeds the target temperature range, not from 0, e.g. If you have an STC-8080A controller to control a compressor,

CodeFunctionMinMaxDefaultUnit
F1Temperature for Startup RefrigeratorF250-10°C
F2Temperature for Stop Refrigerator-40F1-20°C
F3Temperature Calibration-550°C
F4Defrosting Cycle / Interval Time0998Hour
F5Defrosting Lasting /Duration Time09920Min
F6Exceeding Value more than F1 to Trigger Alarm05015°C

set the target temperature from 5 to 10 degrees (F1=10, F2=5), and set the “exceed value” F6 as 6 degrees, the controller will alarm

once the temperature is higher than F1 + F6 = 10 + 6 = 16 degrees or once it is lower than F2 – F6 = 5 – 6 = – 1 ℃

The below tables list all compact panel temperature controllers that own over-temperature alarming functions.

ModelEncodingFunctionSet Temp byInteractiveResolutionMeasurableControllableSensorLoad DelayAlarm MethodsAlarm DelayFan DelayMountingFront PanelAvailable Voltage
STC-200+F Code1 load, refrigeration / Heating / AlarmSP + HysteresisPress1°C-50 to 99°C-50 to 99°C1 Piece 10KΩ NTCEditableAudible and Visible
and External Alarm
N/AN/A71*29 mm77*35 mm220V AC, 110VAC, 12V DC, 24V DC
STC-2301F Code1 load, refrigeration / HeatingHigh-Low limit Touch0.1°C-40.0 to 99.9°C-40.0 to 85.0°C1 Piece 10KΩ NTCEditableAudible and VisibleEditableN/A71*29 mm85*35 mm220V AC, 110VAC, 12V DC, 24V DC
STC-2302F Code2 loads, refrigeration + Defrosting by TimeHigh-Low limitTouch0.1°C-40.0 to 99.9°C-40.0 to 85.0°C1 Piece 10KΩ NTCEditableAudible and VisibleEditableN/A71*29 mm85*35 mm220V AC, 110VAC, 12V DC, 24V DC
STC-2303F Code2 loads, refrigeration + Defrosting by Time and Temp.High-Low limitTouch0.1°C-40.0 to 99.9°C-40.0 to 85.0°C2 Pieces 10KΩ NTCEditableAudible and VisibleEditableN/A71*29 mm85*35 mm220V AC, 110VAC, 12V DC, 24V DC
STC-2304F Code3 loads, refrigeration + Defrosting by Time and Temp.
+ Fan by Time and Temp.
High-Low limitTouch0.1°C-40.0 to 99.9°C-40.0 to 85.0°C2 Pieces 10KΩ NTCEditableAudible and VisibleEditableEditable71*29 mm85*35 mm220V AC, 110VAC, 12V DC, 24V DC
STC-8080A+F Code2 loads, refrigeration + Defrosting by TimeHigh-Low limitPress1°C-50 to 99°C-40 to 50°C1 Piece 10KΩ NTCFixedAudible and VisibleN/AN/A71*29 mm75*34 mm220V AC, 110VAC, 12V DC, 24V DC
STC-8080HF Code2 loads, refrigeration + Defrosting by TimeHigh-Low limitPress1°C-50 to 99°C-40 to 50°C1 Piece 10KΩ NTCEditableAudible and VisibleEditableN/A71*29 mm75*34 mm220V AC, 110VAC, 12V DC, 24V DC
STC-9100F Code or
En Code
3 loads, refrigeration + Defrosting by Time and Temp.
+ Alarm output
SP + HysteresisPress0.1°C-50.0 to 50.0°C-50.0 to 50.0°C2 Pieces 10KΩ NTCEditableAudible and Visible
and External Alarm
EditableN/A71*29 mm75*34 mm220V AC, 110VAC, 12V DC, 24V DC
STC-9200F Code or
En Code
3 loads, refrigeration + Defrosting by Time and Temp.
+ Fan by Time and Temp.
SP + HysteresisPress0.1°C-50.0 to 50.0°C-50.0 to 50.0°C2 Pieces 10KΩ NTCEditableAudible and VisibleEditableEditable71*29 mm75*34 mm220V AC, 110VAC, 12V DC, 24V DC

There are three types of alarming,

  • visible on the screen, default exists in most controllers;
  • audible by an embedded buzzer as the above table shows;
  • external alarm connects to this controller (STC-200 and STC-9100), It should be emphasized that the stc-200 can only alarm through external devices, and F4 must be set to 3, which means switching to the temperature monitoring mode, not the mode of controlling the state of the load power supply.

“High Low” and “Upper Lower”

These two words seem similar and are often misused in English user manuals written by Chinese.

for example,

  • the high/upper temperature could indicate “the temperature to trigger the compressor works” in STC-8080H, it is the upper edge of the target temperature range.
    CodeFunctionMinMaxDefaultUnit
    F1Temperature for Startup RefrigeratorF250-10°C
    F2Temperature for Stop Refrigerator-40F1-20°C
  • But in STC-9200, it indicates the safe range of the target temperature could be adjusted, it is a limitation of the set-point, it is code usually as “HS” or “US”.
    STC-9200 Temperature Controller exist two coding versions,
    the 2nd col. is the acronym of function in English
    the 3rd col. F is abbreviation of the Function,
    Cate.En F FunctionMinDefaultMaxUnitMenu Level
    Temp.SETF01SP (Temperature Set-Point)LS-5US°CUser Menu
    HY F02Temperature Hysteresis / Return Difference1225°C
    US F03Upper limit for SPLS2050°CAdmin Menu
    LS F04Lower limit for SP-50-20US°C
    AC F05Delay Time for Compressor
    Delay time for defrosting (only for thermal air mode)
    0350Min

In another word, it could be the “set range” or “limitation for the set point”.

We need not redefine it but just break it up by the below two lists.

High-Low limit temperature controllers without “limitation for SP”

ModelEncodingFunctionSet Temp byInteractiveResolutionMeasurableControllableSensorLoad DelayAlarm MethodsAlarm DelayFan DelayMountingFront PanelAvailable Voltage
STC-2301F Code1 load, refrigeration / HeatingHigh-Low limit Touch0.1°C-40.0 to 99.9°C-40.0 to 85.0°C1 Piece 10KΩ NTCEditableAudible and VisibleEditableN/A71*29 mm85*35 mm220V AC, 110VAC, 12V DC, 24V DC
STC-2302F Code2 loads, refrigeration + Defrosting by TimeHigh-Low limitTouch0.1°C-40.0 to 99.9°C-40.0 to 85.0°C1 Piece 10KΩ NTCEditableAudible and VisibleEditableN/A71*29 mm85*35 mm220V AC, 110VAC, 12V DC, 24V DC
STC-2303F Code2 loads, refrigeration + Defrosting by Time and Temp.High-Low limitTouch0.1°C-40.0 to 99.9°C-40.0 to 85.0°C2 Pieces 10KΩ NTCEditableAudible and VisibleEditableN/A71*29 mm85*35 mm220V AC, 110VAC, 12V DC, 24V DC
STC-2304F Code3 loads, refrigeration + Defrosting by Time and Temp.
+ Fan by Time and Temp.
High-Low limitTouch0.1°C-40.0 to 99.9°C-40.0 to 85.0°C2 Pieces 10KΩ NTCEditableAudible and VisibleEditableEditable71*29 mm85*35 mm220V AC, 110VAC, 12V DC, 24V DC
STC-8080A+F Code2 loads, refrigeration + Defrosting by TimeHigh-Low limitPress1°C-50 to 99°C-40 to 50°C1 Piece 10KΩ NTCFixedAudible and VisibleN/AN/A71*29 mm75*34 mm220V AC, 110VAC, 12V DC, 24V DC
STC-8080HF Code2 loads, refrigeration + Defrosting by TimeHigh-Low limitPress1°C-50 to 99°C-40 to 50°C1 Piece 10KΩ NTCEditableAudible and VisibleEditableN/A71*29 mm75*34 mm220V AC, 110VAC, 12V DC, 24V DC

Simply speaking, the above temperature controllers only allow users to set a top line and a bottom line to define the target temperature range.

Temperature controllers with “limitation for SP”

ModelEncodingFunctionSet Temp byInteractiveResolutionMeasurableControllableSensorLoad DelayAlarm MethodsAlarm DelayFan DelayMountingFront PanelAvailable Voltage
AL8010FEn Code1 load, refrigeration / HeatingSP + HysteresisPress1°C-50 to 120 °C-50 to 120 °C1 Piece 10KΩ NTCEditableVisibleN/AN/A71*29 mm75*34 mm220V AC, 110VAC, 12V DC, 24V DC
AL8010HEn Code1 load, refrigeration / HeatingSP + HysteresisPress1°C0 to 300 °C0 to 300°C1 Piece 100KΩ NTCEditableVisibleN/AN/A71*29 mm75*34 mm220V AC, 110VAC, 12V DC, 24V DC
STC-100AEn Code1 load, refrigeration / HeatingSP + HysteresisPress1°C-40 to 99°C-40 to 99°C1 Piece 10KΩ NTCEditableVisibleN/AN/A71*29 mm75*34 mm220V AC, 110VAC, 12V DC, 24V DC
STC-200+F Code1 load, refrigeration / Heating / AlarmSP + HysteresisPress1°C-50 to 99°C-50 to 99°C1 Piece 10KΩ NTCEditableAudible and Visible
and External Alarm
N/AN/A71*29 mm77*35 mm220V AC, 110VAC, 12V DC, 24V DC
STC-9100F Code or
En Code
3 loads, refrigeration + Defrosting by Time and Temp.
+ Alarm output
SP + HysteresisPress0.1°C-50.0 to 50.0°C-50.0 to 50.0°C2 Pieces 10KΩ NTCEditableAudible and Visible
and External Alarm
EditableN/A71*29 mm75*34 mm220V AC, 110VAC, 12V DC, 24V DC
STC-9200F Code or
En Code
3 loads, refrigeration + Defrosting by Time and Temp.
+ Fan by Time and Temp.
SP + HysteresisPress0.1°C-50.0 to 50.0°C-50.0 to 50.0°C2 Pieces 10KΩ NTCEditableAudible and VisibleEditableEditable71*29 mm75*34 mm220V AC, 110VAC, 12V DC, 24V DC

The above digital thermostats allowed users to set the aim temperature range by “set-point” and “hysteresis”, you may read ” Target Temperature Range“ if want to learn more.

Although STC-1000 is a thermostat with an SP feature, there are no SP limitation options there.