Electronic Balances rely on the principle of electromagnetic force balancing for precise weighing. When an object is placed on a weighing pan, its gravity causes the coils connected to the weighing pan to displace in the magnetic field. According to the theory of electromagnetism, the energized wire is subjected to an electromagnetic force (ampere force) in a magnetic field, which is proportional to the current intensity and perpendicular to the direction of the magnetic field and current. In this case, the electronic balance adjusts the current in the coil to generate an electromagnetic force equal to the magnitude of the object's gravity and in the opposite direction, so that the weighing pan and the object are in equilibrium. The current value of the coil is proportional to the mass of the object, which is converted electronically to accurately display the mass of the object in digital form.
Key components
The load acceptance and transfer device, the weighing pan, is used to carry the weighed object and transfer the object's gravity to the subsequent measuring component.
Measurement & Compensation – This is the heart of an electronic balance and consists of displacement sensors, regulators, amplifiers, etc. The displacement sensor monitors the displacement change of the weighing pan due to the gravity of the object in real time, transmits the signal to the regulator and amplifier, and then adjusts the coil current, realizes electromagnetic force compensation, and maintains the equilibrium state.
Single-module sensors – revolutionizing electronic balance technology – began in the early 90s of the 20th century. The new generation uses high-precision EDM wire cutting technology, selects aviation aluminum alloy, and the parts are greatly reduced, with a resolution of 1/2000, which is 10 times that of the traditional electromagnetic balance. It has a strong overload and anti-siderush device, resists 100kg instantaneous impact force, improves the pass rate, and is convenient to maintain and low cost.
Procedure
To use a balance, follow these steps. First of all, adjust the level, carefully adjust the height of the anchor bolts, and make the internal air bubble in the center of the ring according to the level, laying the foundation for accurate weighing. Then turn on the preheating, turn on the power and press the on/off key, the balance is full-screen self-test, after the first or long-term power failure, preheat according to the model requirements, at least 30 minutes, some even take more than 2.5 hours, it is recommended to keep standby. Then calibrate the operation, press the correction key when starting to use or regular maintenance, place the corresponding weight according to the display, and complete the correction to ensure the accuracy of the data when the display "g" is displayed. Then weigh the sample, press the peeling button to clear the weighing pan, place the sample steadily, and wait for the value to be stable and read the record. Finally, shut down for maintenance, if you don't use it for the time being, you can turn it off and cut off the power supply if you don't use it for a long time, but you should turn on the power regularly.
Classification of species
Categorized by use
Upper Dish Electronic Balance: The weighing pan is located on the top of the balance, which is easy to use, and is often used in routine weighing scenarios, such as basic experiments in school laboratories, factory raw material weighing, etc.
Electronic analytical balances: extremely high precision, mainly used in scientific research, pharmaceutical, chemical industry and other fields with strict requirements for measurement accuracy, can meet the experimental needs of micro and constant analysis.
Electronic microbalance: Focus on the accurate weighing of a very small number of samples, the maximum weight is usually within a few grams, and the graduation value is very small, which is often used for ultra-micro analysis work such as the determination of trace components of biological samples.
Classified by precision
Ultra-micro electronic balance: the maximum weight is generally from 2 to 5g, and the scale index value is less than 10⁻⁶ of the (maximum) weighing, which is suitable for scientific research scenarios for high-precision weighing of very trace substances.
Microbalances: The weighing range is generally from 3 to 50g, and the index value is less than 10⁻⁵ of the (maximum) weighing, which is often used in experiments with high precision requirements for micro samples.
Semi-micro balances: Weighing ranges from 20 to 100 g with a graduation value less than 10⁻⁵ (maximum) for semi-micro analysis experiments.
Constant electronic balance: The maximum weight is usually between 100 and 200g, and the graduation value is less than 10⁻⁵ of the (maximum) weighing, which is widely used in various scenarios of macro material weighing.
Analytical Balances: Covers constant, semi-micro, micro, and ultra-micro balances, and is a general term for precise analytical experiments.
Precision electronic balance: The accuracy level is level II., which is suitable for general weighing work with high requirements for accuracy, and is more common in industrial production quality testing, routine laboratory analysis and other scenarios.
Notable features:
The electronic balance far surpasses the traditional mechanical balance in terms of stability and durability, abandoning gemstones, agate knives and knife bearings, using spring sheet support and canceling the lifting frame device, and using large integrated circuits, which not only reduces wear and tear, prolongs service life, but also makes the structure compact and stable performance; The weighing is based on the principle of electromagnetic force balance, which can be quickly and accurately read in seconds without weights, and some products equipped with monolithic microprocessors further optimize the relevant performance; In terms of operation, it has rich practical functions such as automatic correction to simplify the process and improve efficiency; It also has the function of quality signal output, through the RS232C standard interface can be easily connected to printers, computers and other equipment, to achieve automatic data recording and other operations, and even can be used with other analytical instruments to build a fully automated workflow, taking the electronic balance digital Recorder of Shanghai Tianping Instrument Factory as an example, its functions are diverse and the printing speed is up to 1.3 lines/s, which greatly improves the production efficiency.
In summary, electronic balances use the principle of electromagnetic force balance to generate an electromagnetic force that competes with the gravity of an object by adjusting the current in the coil connected to the weighing pan to achieve accurate weighing. Key components, such as single-module sensors, dramatically improve performance, reduce the number of parts, and enhance stability and durability. It offers a number of advantages, such as stability and durability far beyond traditional mechanical balances, fast and accurate readings, practical functions such as automatic calibration, and the ability to connect to external devices. During operation, it is necessary to complete the leveling, start-up preheating, calibration, weighing and shutdown maintenance in turn. According to the use, it can be divided into dish, analysis, and micro balance; According to the accuracy, it can be divided into ultra-micro, micro, semi-micro, constant electronic balance, analytical balance and precision electronic balance, which are widely used in scientific research, production, teaching and other fields to meet different accuracy requirements.
