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Common Terminology Resistance
Apr 06, 2017

Common terminology resistance


Critical resistance value Critical Resistance Value
    The maximum nominal resistance at rated load power can not exceed the maximum operating voltage.
Rated voltage equal to the critical resistance value of the maximum operating voltage.
Derating Curve derating curve
    Derating curve for the ambient temperature and maximum continuous load power in the relationship between its operating temperature, which is usually expressed as a percentage.Insulation withstand voltage Dielectric Withstanding Voltage Insulation withstand voltage is applied to the resistance between the specified element and an outer coating, or a resistive element and the mounting surface, it does not cause a breakdown.
The maximum overload voltage Maximum Overload Voltage 

    The maximum load on the resistor voltage value in a short time overload test. Normally loads in a short time overload voltage is 2.5 times the rated voltage.
Maximum operating voltage Maximum Working Voltage (or Maximum Limiting Element Voltage)
    Maximum sustainable applied to the resistor or resistor assembly DC or AC voltage, maximum voltage that can be loaded to the rated voltage at the critical resistance value or less resistance.Noise, noise Noise Resistor noise at the low level signal, having a great impact, such as charge amplifiers, high-gain amplifiers, and other noise-sensitive applications. Noise or noise due to the resistance of the structure and process produced ,, best method is to use a low-noise type of resistor for highly sensitive products.Power Definition Power Rating
    Power according to physical size, allowable change in resistance in the life of the material thermal conductivity, insulation and resist material and ambient operating conditions. For best results, below its maximum rated temperature and power, the maximum size of the use of physical resistance. Never use the highest continuous power rating, unless you are willing to accept resistors shortened life changes. If the circuit design license, choose a high value resistor or divider network will reduce power consumption and improve the level of performance of the resistor, because the resistance is in the low power level.Rated ambient temperature Rated Ambient TemperatureMaximum ambient temperature can continue to be used under the resistor power rating prescribed.Rated ambient temperature is the temperature around the resistors inside the equipment, rather than the outside temperature equipment.Rated Power Rated Power Maximum power loading of the resistor can be sustained in the nominal ambient temperature. Resistor networks and arrangement of the resistor rated power resistor composition is consistent with each of them.
    Rated Voltage Rated VoltageMaximum sustainable composition is applied to the resistor or resistor DC or AC voltage to the rated ambient temperature.Reliability Reliability Reliability is a resistor (or any other element) to perform the function of the probability of having.There are two methods to determine reliability. The first is between failures (MTBF) mean time, the second is the failure rate per 1000 hours of operation.
Reliability Evaluation of these two methods, you must determine the test and define specific groups of what is the final element life, such as the resistance value of the maximum amount of change, or short-circuit or open circuit.Application of statistical methods to arrive at these failure rates, and a large number of samples tested at maximum rated temperature and rated load continuous 10,000 hours (24 hours a day, approximately 13 months).When using a low power level, generally higher reliability.Resistance Tolerance Resistor Tolerance
     Resistance tolerance expressed as a percentage deviation from the nominal value, at 25 ° C and measured at the same time does not load any power.Resistor value will decrease as the applied voltage (VCR) and temperature (TCR) is changed.For network resistors absolute resistance tolerance refers to the entire network of resistance total resistance tolerance.Tolerance refers to the proportion of each resistor relation to the whole package.
Stability Stability
    Stability refers to the period of time of the load, humidity, pressure, or the resistance changes in ambient temperature. As these outside pressures contained a minimum, better stability.Rated temperature Temperature Rating Rated temperature is the maximum allowable temperature resistance can be used. General definition of two temperatures.For example, the full load resistor to + 70 ° C, and then began to load without derating to + 125 ° C.This means that some allowable change in resistance throughout the life cycle of resistance, it is possible to work at rated power + 70 ° C.Resistance can also be above + 70 ° C temperatures, if the load is reduced, then. However, without exception, the temperature should not exceed the design temperature + 125 ° C, which contains the ambient temperature and self-heating power.Resistor voltage coefficient Voltage Coefficient of Resistance (VCR)
     Voltage coefficient is the amount of change in the resistance value of the applied voltage. This is completely different from the power leads to self-heating effects of resistance. Resistor VCR 100 ppm / V variation will change 0.1% / 1% and 10 Volt / 100 Volt change. The rates of change for each volt resistance value as shown 

in Equation:
VCR (ppm / V) = (Ro - R) / Ro × 1 / (Vo - V) × 106
R: Under the reference voltage measurement Resistance (Ω); V: voltage reference
Ro: high voltage resistance measurement (Ω); Vo: High Voltage
Buffer circuit applications Snubber circuits
     Familiar and low inductance winding carbon crystal and thin film resistors are often not maintained in good condition in high voltage, high current, or high-energy conditions.To use the buffer circuit applications, for example, compare these resistors and ceramic resistance results show that does not match the performance and reliability.Since the power consumed in a very short peak instantaneous peak power can be measured by many megawatts.
     Due to the small mass of the resistive element, film and wirewound resistors in thermal shock and susceptible to degradation and aging, compromise product equipment.Even so-called non-inductive wire wound resistors also show some small amount of sense, obvious sense about tens to hundreds of Hertz with the old design.
However, the high running speed applications such as today's power conversion systems, can make these resistors become powerless, because of the need nH low inductance.Organic solid core resistors are non-inductive and provide appropriate solutions, low average power, but sometimes a high voltage or moisture can cause them unstable.Solid resistance rated power of up to 2 watts Temperature Coefficient of Resistance Temperature Coefficient of Resistance (TCR also known as RTC)Temperature coefficient of resistance (TCR) expressed as a change in resistance in ppm (0.0001%) per degree Celsius temperature change (° C).
E.g., +100 ppm / TCR ° C change resistor and + 0.1% in the total amount of change of 10 degrees, and 1% to the sum of 100 degree change ratio.
      In the book quoted TCR specifications are usually referenced in + 25 ° C and + 25 ° C to + 75 ° C temperature coefficient curve. The temperature coefficient TCR is usually not linear but parabolic with increasing temperature. The circuit designers generally, considered as the linear temperature coefficient curve, unless it is necessary to very accurate measurements. US military regulations standards (MIL STD 202 Method 304) is a standard TCR measurement methods. The following formula expresses the resistance value of the rate of          change of 1 ° C in a predetermined temperature range:
TCR (ppm / ° C) = (R - Ro) / Ro × 1 / (T - To) × 106
R: measured resistance value (Ω) at T ° C; Ro: resistance measurement (Ω) at To ° C

T: measured temperature (° C); To: measuring temperature (° C) at To ° C
      Resistor network in context, this is called the absolute TCR TCR value, which defines the specific TCR resistor network unit of resistance.Learn resistance temperature coefficient of Understanding Temperature Coefficient of Resistance