PTC Thermistor
A thermistor with a positive (PTC) or negative (NTC) temperature coefficient.
blockType: AcausalElectricPowerSystems.Sensors.Thermistor
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PTC Thermistor Path in the library: |
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Thermistor Path in the library: |
Description
Block PTC Thermistor It is a thermistor with a positive (PTC) or negative (NTC) temperature coefficient.
Thermistor with negative temperature coefficient (NTC)
A thermistor with a negative temperature coefficient (NTC) uses the B-parameter equation.
For an NTC thermistor, resistance at temperature It is defined as follows:
,
where:
-
— resistance at nominal temperature .
-
— temperature coefficient.
Typical thermistor usage in models:
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Connect the thermistor to the B port of the Convective Heat Transfer unit.
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Connect the A port of the Convective Heat Transfer unit to the Ideal Temperature Source unit, whose temperature is set to ambient temperature.
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Set the Area parameter of the Convective Heat Transfer block to the approximate area .
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Set the Heat transfer coefficient parameter of the Convective Heat Transfer block to .
Thermistor with a positive temperature coefficient (PTC)
The resistance of this type of thermistor decreases with increasing temperature to the Curie temperature. Above the Curie temperature, the resistance increases very rapidly with increasing temperature, as shown in the following graph. The area to the right of the Curie temperature is called the PTC mode.
For a PTC thermistor, resistance at temperature It is defined as follows:
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- the Curie temperature.
-
- resistance at nominal temperature .
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- resistance at the reference temperature .
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- the nominal temperature at which the resistance is indicated, usually room temperature. less Curie temperature .
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- reference temperature equal to or higher than the Curie temperature , which means that the PTC mode is in effect at this temperature.
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- temperature coefficient at nominal temperature .
-
- temperature coefficient at the reference temperature .
The following equation describes the thermal behavior of the block:
,
where:
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- heat flow in port A.
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— dispersion coefficient, the value of the Dissipation factor parameter.
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— time constant, the value of the parameter Thermal time constant.
-
— the rate of temperature change.
Ports
A — thermal port
warm
The thermal port that determines the temperature of the resistor.
+ — positive
electricity
The electrical port represents the positive terminal of the resistor.
− — negative
electricity
The electrical port represents the negative terminal of the resistor.
Parameters
Electrical
Block type — selection of the type of thermistor
Thermistor (default) | PTC Thermistor
Choosing the type of thermistor
-
Thermistor— a thermistor with a negative temperature coefficient (NTC). -
PTC Thermistor— thermistor with a positive temperature coefficient (PTC).
Nominal resistance R0 at reference temperature T0 — resistance at nominal temperature
1000 Ohms (default)
The resistance of the thermistor at the nominal temperature. Many specifications specify a resistance at 25°C (298.15 K); denoted R25.
Dependencies
To use this parameter, set the Block type parameter to Thermistor.
Characteristic temperature constant B — constant temperature coefficient
3500 K (default) | positive scalar
Ratio in the equation describing resistance as a function of temperature.
Dependencies
To use this parameter, set the Block type parameter to Thermistor.
Reference temperature T0 — nominal temperature
298.15 K (default) | positive scalar
The temperature at which the nominal resistance was measured.
Dependencies
To use this parameter, set the Block type parameter to Thermistor.
Nominal resistance R0 at T0 — resistance at nominal temperature
1000 Ohms (default)
The resistance of the thermistor at the nominal temperature. Many specifications specify a resistance at 25°C (298.15 K); denoted R25.
Dependencies
To use this parameter, set the Block type parameter to PTC Thermistor.
Temperature coefficient alpha0 at T0 — temperature coefficient at nominal temperature
-0.01 1/K (default) | negative scalar
Ratio in an equation describing resistance as a function of temperature at a nominal temperature. The value must be less than zero.
Dependencies
To use this parameter, set the Block type parameter to PTC Thermistor.
Nominal temperature T0 — nominal temperature
298.15 K (default) | positive scalar
The temperature at which the nominal resistance was measured.
Dependencies
To use this parameter, set the Block type parameter to PTC Thermistor.
Reference resistance R1 at T1 — reference resistance at reference temperature
10000 Ohms (default)
The reference resistance of the thermistor at the reference temperature.
Dependencies
To use this parameter, set the Block type parameter to PTC Thermistor.
Temperature coefficient alpha1 at T1 — temperature coefficient at the reference temperature
1 1/K (default) | positive scalar
Ratio in an equation describing resistance as a function of temperature at a reference temperature. The value must be greater than zero.
Dependencies
To use this parameter, set the Block type parameter to PTC Thermistor.
Reference temperature T1 — reference temperature
398.15 K (default) | positive scalar
The temperature at which the reference resistance is measured. This temperature should be in PTC mode.
Dependencies
To use this parameter, set the Block type parameter to PTC Thermistor.
Thermal
Thermal time constant is the time constant for the thermal equation
5 s (default) | positive scalar
The time it takes for the temperature of the resistor to reach 63% of the final temperature change with an abrupt change in ambient temperature.
Dissipation factor is the coefficient of dissipation for the thermal equation
0.75E-3 W/K (default) | positive scalar
The thermal power required to increase the temperature of the thermistor by 1 K.