What Is a Power Resistor?

The resistance of a conductor to current is called its resistance. In physics, resistance is used to indicate the magnitude of the resistance of a conductor to current. The greater the resistance of a conductor, the greater the resistance of the conductor to current flow. Different conductors generally have different resistance. Resistance is a property of the conductor itself.

Power resistance

Power refers to the work that an object does in a unit of time, that is, power is a physical quantity that describes the speed at which work is performed.

The formula for finding power is power = work / time, and the formula is

P represents power in units of "

Power measurement is used to measure the power consumed by electrical equipment, and is widely used in research and development or production lines, such as household appliances, lighting equipment, and industrial machinery. This article focuses on several power measurement methods and their specific applications.

1

The resistance of a conductor to current is called the resistance of the conductor. (The pictures on the right are JEPSUN chip resistors, respectively.

a. According to the resistance characteristics: fixed resistance, adjustable resistance, special resistance (sensitive resistance).

What we can't adjust, we call it fixed resistance, and what we can adjust, we call it

a. Correctly select the resistance and error of the resistor:

Resistance selection: the principle is the resistor used

Object resistance calculation formula: R = L / S, where L is the length of the object and S is the cross-sectional area of the object.

Nominal value series

E24 (error ± 5%): 1.0, 1.1, 1.2, 1.3, 1.5, 1.6, 1.8, 2.0, 2.2, 2.4, 2.7, 3.0, 3.3, 3.6, 3.9, 4.3, 4.7, 5.1, 5.6, 6.2, 6.8, 7.5, 8.2, 9.1

E12 (error ± 10%): 1.0, 1.2, 1.5, 1.8, 2.2, 2.7, 3.3, 3.9, 4.7, 5.6, 6.8, 8.2

E6 (error ± 20%): 1.0, 1.5, 2.2, 3.3, 4.7, 6.8

Nominal rated power:

Wirewound resistor series: 3W, 4W, 8W, 10W, 16W, 25W, 40W, 50W, 75W, 100W, 150W, 250W, 500W

Non-Wirewound Resistor Series: 0.05W, 0.125W, 0.25W, 0.5W, 1W, 2W, 5W

English explanation:

Resistance means the inhibition from conductor to current. The symbol of resistance is (R) and the unit of resistance is (?).

Resistance calculation formula: R = U / I = U square / P

Pick up

According to the Ministerial Standard (SJ-73), resistors,

Correct selection of resistor value and error

Resistance value selection: The principle is that the smaller the difference between the nominal resistance value of the resistor used and the required resistance value, the better.

Error selection: The error of the resistor required for the time constant RC circuit is as small as possible. Generally selectable within 5%. For decoupling circuits, feedback circuits, filter circuits, load circuits, the error requirements are not too high. Optional 10% -20% resistor.

Pay attention to the limit parameters of the resistor

Rated voltage: When the actual voltage exceeds the rated voltage, even if the power requirements are met, the resistor will be damaged by breakdown.

Rated power: The rated power of the selected resistor should be more than twice the actual power to be guaranteed to ensure the long-term reliability of the resistor in the circuit.

Preferred General Purpose Resistors

There are many types of general-purpose resistors, complete specifications, large production batches, and resistance ranges, appearance shapes, and volume sizes have room for selection, which is easy to purchase and maintain.

Select according to circuit characteristics

High-frequency circuit: The smaller the distribution parameter, the better. High-frequency resistors such as metal film resistors and metal oxide film resistors should be selected.

Low frequency circuit: Both winding resistance and carbon film resistance are applicable.

Power amplifier circuit, bias circuit, and sampling circuit: The circuit has relatively high stability requirements, and a resistor with a small temperature coefficient should be selected.

Decoupling circuit and filter circuit: There is no strict requirement for resistance change, and any type of resistor is applicable.