Why Choose Tiangeng
Professional Production
We are a company specializing in the design, development, and production of precision series resistors, precision sampling resistors, precision shunts, precision resistor dividers, non-inductive resistors, and power resistor.
Strict Management System
We implement a high-tech enterprise quality management system and strictly follow ISO9001 service management standards and work processes. We will establish detailed product files for customers, respond to customer service requests on time, and assist customers in solving problems.
Advanced Equipment
We have advanced production equipment, such as precision photolithography machines, high and low temperature testing equipment, Agilent 3458A and other precision instruments, digital high-resistance calibrators, high-temperature sintering equipment, heat treatment equipment, etc.
Wide Application
The products produced are widely used in sensors, scales, rail transit, ships, new energy, precision automation control, power instruments, medical equipment, power automation control, precision instruments, measuring instruments, automobiles, electromechanical railways, communications and other fields.
What is Standard Resistor?
A standard resistor is a passive two-terminal electrical component that implements electrical resistance as a circuit element. It is used to limit the amount of current flowing in an electric circuit and to lower voltage levels within circuits. Standard resistors are available in various resistance values and power ratings, and they are commonly used in electronic and electrical circuits for various applications.
What Is a Standard Resistor Value?
First defined in 1952 by the IEC (International Electrotechnical Commission), resistor values aim to standardize the resistance and tolerance of resistors across the world. This makes it easier for consumers and electrical engineers to pick the right components for their circuits. It also provides manufacturers with a template to follow. A standard surface-mount resistor's ohmage and tolerance can be found by reading resistor color codes.
Preferred values, also known as E-series, are split into groups based on their tolerance. The tolerance of a resistor describes the potential difference between its rated resistance and its actual resistance. For example, an E3 series resistor has a tolerance of 40%. This means that an E3 resistor with a resistance rating of 100 ohms will actually have a resistance between 60 and 140 ohms. Each series is split further into a set of resistance values.
Properties of Standard Resistor
Power Rating
The power rating indicates the maximum dissipation that the component is capable of. The rated dissipation is normally specified at room temperature and decreases at higher temperatures. This is called derating. Typically, derating is specified above 70 °C. Above this temperature, the resistor can only safely operate at a reduced power level.
Noise
For some resistors it is important to have low noise properties. Resistor noise is primarily dependent on 3 parameters: resistance, temperature and bandwidth. A high-gain amplifier is an example where noise must be low.
Frequency Dependence
The parasitic inductance and capacitance of a resistor become increasingly important when the frequency increases. A resistor has good high frequency properties when, for the required operating frequency range, the parasitic effects are negligible.
Insulation of the Wires
Wirewound resistors are enamel insulated (possibly winded with synthetic fiber, silk or cotton) and the oxide layer of the material itself.
Electrical Resistivity of the Material
Many different materials and alloys with different values of resistivity are used to create resistors. The resistivity of the material influences the size of the resistor.
Maximum Allowed Voltage
If the maximum allowed voltage is exceeded, it may cause a disruptive electrical discharge permanently damaging the wire insulation. Also, a discharge can pass through the solid insulating material and damaging parts that are nearby.
Long Term Stability
The stability indicates the maximum tolerable change of the resistance value. The resistance value changes in the long term due to mechanical, electrical and thermal loads. In standards, several stability classes are determined. The standards define tests to define the stability classes.
Thermo-electric Effect
Because different materials are used for the mounting wire and the resistor material, the thermo-electric effect causes unwanted electric currents. Precision resistors are carefully manufactured to minimize the thermo-electric effect.
- Resistors can be constructed out of a variety of materials. Most common, modern resistors are made out of either a carbon, metal, or metal-oxide film. In these resistors, a thin film of conductive (though still resistive) material is wrapped in a helix around and covered by an insulating material. Most of the standard, no-frills, through-hole resistors will come in a carbon-film or metal-film composition.
- Other through-hole resistors might be wirewound or made of super-thin metallic foil. These resistors are usually more expensive, higher-end components specifically chosen for their unique characteristics like a higher power-rating, or maximum temperature range.
- Surface-mount resistors are usually either thick or thin-film variety. Thick-film is usually cheaper but less precise than thin. In both resistor types, a small film of resistive metal alloy is sandwiched between a ceramic base and glass/epoxy coating, and then connected to the terminating conductive edges.
What Do Resistors Do in a Circuit?
Potential Dividers
Two or more resistors in series will give a voltage at their junction point proportional to the ratio of their values. This functionality is widely used in circuits for generating intermediate voltages.
Biasing Resistors
Transistors and many other devices need to have their AC and DC operating characteristics and gain values set up for correct operation. This is done with multiple resistors and is often called biasing.
Op-Amp Gain And Feedback
Most op-amp circuits need to have their gain and feedback functionality set by resistors external to the amplifier chip; resistors are the primary means of doing this.
Current Limiting
Resistors can be used to limit the amount of current that flows in a circuit element. This is a useful safety function in many circuits e.g. limiting the current that can flow into an LED to manage its brightness.
Impedance Matching
To maximise power transmission at high frequencies the impedance of the receive and transmit ends of a circuit need to be the same. Resistors can perform at least part of this requirement.
Current Measuring
Many circuits need to know how much current is flowing, however, it is much easier to measure voltage, so inserting a resistor into the circuit to ‘develop’ a voltage – remember Ohm's law- is a common technique for measuring current.
Data And Address Bus Pullups
This functionality helps to reduce noise issues on high-speed computer busses. When a data bus tri-states or is driven high, it is often necessary to pull it into a known state or to make sure its output high is well above the switching point of other logic elements on the bus, and a pull up helps to do this.
How to Test Resistors
1.Remove Power From the Circuit Containing the Resistor. This can be done by unplugging it from the mains or by removing the batteries if it is a portable device. Keep in mind that some devices still can be charged with a potentially harmful voltage until minutes after removing its power!
2.Isolate the Resistor From the Circuit. An attempt to measure a resistor that is still connected to the circuit can yield an incorrect calculation, as part of the circuit might also be measured.
3.Inspect the Resistor. If the resistor shows signs of blackening or charring, it may be damaged by excess current flow. A resistor showing blackening or charring should be replaced and discarded.
4.Read the Resistor Value Visually. The resistor value will be printed on the resistor. Smaller resistors may have their value indicated by color coded bands.
5.Prepare a Digital Multimeter (Dmm) to Measure the Resistor. DMMs are available at electronics parts and hobby stores. Ensure that the DMM comes on and does not indicate a low battery condition.
6.Measure the Resistance. Connect the 2 leads of the DMM to the 2 legs of the resistor. Resistors have no polarity, so it does not matter which DMM lead is connected to which resistor leg.
7.Determine the Actual Resistance of the Resistor. Read the result shown on the multimeter. In determining whether or not the resistor is within the allowable range for that resistor, do not forget to take the resistor tolerance into account.
8.Reattach a Resistor That Gives An Accurate Reading. Reconnect it to the circuit by pressing it back into place if you pulled it free with your fingers. If the solder joint had to be melted and the resistor had to be disconnected using pliers, melt the solder with the soldering iron and use the needle nose pliers to push the resistor back in to place.
9.Replace a Resistor That Measures Outside of the Acceptable Value Range. Discard the old resistor. Resistors are available in electronics parts stores and hobby stores. Note that replacing the malfunctioning resistor will not necessarily fix the problem, if the resistor fails again the source of the problem should be sought elsewhere in the circuit.
How to Read Resistor Color Code?
Colors and Their Corresponding Values
A numeric value is associated with each color, Simply match the colors on your resistor with the corresponding values in the table, and you’ll have the resistance value right at your fingertips.
Significant Digits
The first two bands represent the significant digits of the resistors resistance value. For example, if the first band is brown and the second band is black, the resistor's resistance value starts with the digits “1” and “0”, which means 10 ohms.
Multiplier Band
The third band represents the multiplier that needs to be applied to the significant digits to obtain the final resistance value. It is crucial for resistors with values greater than 10 ohms since the value alone would be too small.
Tolerance Band
For precision resistors, a fourth band is present, indicating the tolerance of the resistor's resistance value. Tolerance refers to the permissible deviation from the specified resistance value.
How do You Choose the Standard Resistor?
Calculating Your Required Resistance
This is where you will use Ohm's Law to calculate your resistance. You can use one of the standard formulas below when your voltage (V) and current (I) are known.
Calculating Your Power Rating
Next, you need to figure out how much power your resistor is going to need to dissipate. This can be calculated with the following formula: P=V2/R. In this formula, P is your power in Watts, V is the voltage drop across the resistor, and R is the resistance of the resistor in Ohms.
Choosing a Resistor
Now that you have your resistance and power rating values, it's time to pick an actual resistor from a component distributor. We always recommend sticking with standard resistors that will be carried in stock by every distributor. Staying with standard resistor types will make your life a whole lot easier once it's time to manufacture.
Preventive Maintenance for Standard Resistor
Every 6 Months
- Visual inspection of ventilation ducts.
- Checking the ohmic values of the resistors.
- Checking the tethering of the powered parts.
Insulation control
Dielectric test
No-load test
Intervention report
Once a Year
Visual inspection of ventilation ducts.
Checking the ohmic values of the resistors.
Power part tightening control.
Thermographic check of connections.
Measurement for validation of powers.
Load test (25% / 50% / 75% / 100%).
Insulation control.
Empty test.
Test report.
Every 3 Years
Extraction of ventilation ducts for:
Check the ohmic values of the resistors.
Control of the tightening of the power parts.
Insulation test / Dielectric test.
Fan check.
Replacement of glass mats.
Replacement of glass mats.
Repair of air duct seals.
Soft PLC update.
No-load test.
Our Factory
Based on many years of producing various precision resistors, our company designs, develops, and produces various resistor cabinets, coaxial resistors, and metal foil standard resistors.
Company Honor
Based on the high-tech enterprise quality management system, we strictly follow ISO9001 service management standards and work processes.
Frequently Asked Questions
We're well-known as one of the leading standard resistor manufacturers and suppliers in China. If you're going to buy or wholesale high quality standard resistor made in China, welcome to get more information from our factory.
standard resistor wattage, High power Standard Resistor, Measurement Standard Resistance