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TECHNICAL SUPPORT
Cap /Sensor Comparison / R-T Curve / Glossary / Caution /
Cap¡¯s Materials, Characteristics and Application
| SN | Cap Materials |
Model |
Characteristics |
Application |
1 |
ABS |
SP1 |
Damp proofing, Antisepsis, Low cost, Enduring voltage |
Icebox, Air-conditioner |
2 |
PVC |
SP2 |
||
3 |
PP |
SP3 |
||
4 |
PA6 |
SP4 |
||
5 |
Copper |
SC1 |
Damp proofing, Heat transmitting, Enduring temperature shock. |
Air-conditioner, Water heater, |
6 |
Nickel plated copper |
SC2 |
Damp proofing, Heat transmitting, Enduring temperature shock, Antisepsis |
|
7 |
Stainless steel |
SS1 |
Intensity, Damp proofing, Enduring temperature shock, Antisepsis, High temperature application |
Home electric appliance, Barbecue, Refrigeratory |
Practical Cap¡¯s size
| Materials | Diameter£¨mm£© |
Length£¨mm£© |
|
Plastic Shell |
5£¬7£¬9 |
25£¬30£¬50£¬ |
(Client decides) |
Copper Shell |
4£¬5£¬6£¬8 |
20£¬25£¬30£¬45 |
|
Stainless Steel Shell |
3£¬4£¬5£¬6£¬7£¬8 |
20£¬25£¬30£¬45 |
Comparison with different temperature sensors
Sensor Type |
NTC Thermistor sensor |
Winding Pt Sensor |
Film Pt sensor |
Semiconductor IC sensor |
Materials |
Ceramic |
Winding Pt wire |
Film Pt |
Silicon |
Relative cost |
Low |
High |
Middle |
Middle |
Temperature range |
-100~500¡æ |
-200~600¡æ |
-150~500¡æ |
-55~150¡æ |
Sensitivity |
-4%/¡æ |
0.39%/¡æ |
0.39%/¡æ |
0.81%/¡æ |
Relative sensitivity |
Very high |
Very low |
Very low |
Low |
Linearity |
Logarithm |
Linearity |
Linearity |
Linearity |
Allowed current |
Small |
Big |
Relatively big |
|
Slope |
Negative |
Positive |
Positive |
Positive |
Professional Glossary for Thermistor Temperature Sensor
A. Zero Power Resistance Value
The zero-power resistance is the resistance value of a thermistor measured at a specified temperature with power dissipated by the thermistor low enough that any further decrease in power will result in not more than 0.1% (or one tenth of the specified measurement tolerance, whichever is smaller) change in resistance.
Nominal Resistance (Rated zero power resistance) R25
Zero power resistance value at 25¡æ
B. B Value
The material constant of a thermistor, Unless otherwise specified, Beta is derived from thermistor resistance measurements obtained at 0¡ã and 50¡ãC.
RT1=Zero power resistance at T1; RT2=Zero power resistance at T2
C. Dissipation coefficient ¦Ä
The dissipation constant is the ratio, (expressed in milliwatts per degree C) at a specified ambient temperature, of a change in power dissipation in a thermistor to the resultant body temperature change.
¦Ä =¦¤P/¦¤T
D. Thermal time constant ¦Ó
The thermal time constant is the time required for a thermistor to change 63.2% of the total difference between its initial and final body temperature when subjected to a step function change in temperature under zero-power conditions.
Cautious About Using Temperature Sensor
To avoid quick aging acute temperature change should be shun.
To avoid temperature error and product damage we should minimize the current passing through the sensor when designing the circuit.
To avoid error Thermistor should be measured in the constant temperature vessel.