Rating of the best strain gauges for 2024

Pressure and weight load cells are those devices from the field of weighing technology that are capable of converting the mechanical deformation of objects and bodies into a conventional electrical signal, which subsequently allows you to determine the level of compression / expansion of a particular body. By itself, such a sensor is a resistive converter and is positioned as one of the main components of high-precision weighing equipment. These devices are used in any electronic type scales: from household floor-mounted to ultra-precise laboratory scales.

The principle of operation of a strain gauge is as follows: when an object is placed on the scale, under its influence (weight) the resistor on which the strain gauge is installed changes (deforms). In turn, the sensor measures the force and the amount of deformation of the resistor and transmits this data to the control board. Thus, the weight of the item on the loading platform is calculated. One or more sensors can be used in weighing equipment.

Correctly such sensors in the engineering environment are called weighing meters for scales, and in the common people are called "beams".

Main characteristics

Any strain gauge has a certain set of characteristics that affect the scope and limits of its application. These include:

• "LUI" or the largest measurement limit is the force the device can fix at the maximum. In fact, the sensor itself, of course, has an extended safety margin, but in order to obtain accurate data, it is not recommended to exceed the NPI value set by the manufacturer. If you need to obtain ultra-high-precision results, you must use a device with an additional ATI.
• By their design, these devices can be divided into several types - bridge and single-point, beam and bellows, column and S-shaped, as well as washer. The use of a specific type of construction will depend on the purpose of the weighing system in which the device is supposed to be used, and it is also necessary to take into account the features of the future location of its location.
• According to the connection diagram, strain gauges can be subdivided into "four-core" and "six-core". The first scheme is used in standard cases and under normal conditions, and the second is used when there is a significant difference in the resistance of the cables of adjacent sensors, because it allows you to compensate for their electrical resistance.
• Accuracy class - for the described devices it is quite wide and according to OIML R 60-2000 (State system for ensuring the uniformity of measurements in the Russian Federation), it usually varies from D1 to C6. The most popular in terms of the breadth of application is the C3 class, which is approximately equal to the statistical error of 0.02%. The use of instruments with a lower error requires specific justification. Among other things, the weighing terminal itself can influence the measurement accuracy.
• The material of manufacture of the device - as a standard for this, aluminum, alloy steel or ordinary "stainless steel" are used. Speaking about different designs, it can be noted that single-point, as a rule, are made on an aluminum base, but other models prefer alloy steel. "Stainless steel" is considered a more expensive material and it is used for devices that are used in critical industries, for example, in the food industry.

When selecting a sensor for use for specific purposes, it is also necessary to pay attention to additional characteristics, which include:

• Electrical protection class;
• Working temperature range;
• Working gear ratio (abbreviated as "KRP");
• Maximum possible supply voltage;
• Input / output resistance;
• Section diameter and length of the electrical cable.

More about existing designs

In general, the described device is a single elastic system, consisting of a resistor and an electrical circuit, which is connected to the weighing batcher. When the resistance of the resistor is changed, the level of deformation is set, after which the obtained data are transformed into the required mathematical and physical values ​​and are displayed on the balance display. This is how all electronic weighing equipment functions. Its sufficient accuracy will be maintained even in the event that one of the sensors fails, because the circuits used today imply duplication of measurements.

Depending on the type of weighing pan (or, more correctly, a load-receiving platform), there are the following types of strain gauges:

• Cantilever type - a system with a measuring limit of up to 7 tons is used as measuring elements;
• Single point devices, that is, operating on one sensor - they are used for dosing, filling and other operations where a large load is not required;
• S-shaped devices - they are intended for equipment of a bunker type and proportionally convert the mechanical force of stretching / compression into an electrical signal;
• Cylindrical devices - used in multi-ton control and measuring systems;
• High-temperature devices - used in the manufacture of measuring instruments that operate in extreme ambient temperatures, such as in the smelting or metallurgical industry.

The main requirements for strain gauge devices are moisture resistance, low susceptibility to aggressive media, calculation for a long service life. In addition, the sensors must be sensitive to any increased mechanical stress.

The main difference between a 4-wire sensor and a 6-wire sensor

If the dimensions of the weighing equipment itself are too large, it may happen that the connection between the sensor and the analog-to-digital converter of the equipment will be made using extended wires. Therefore, the readings will begin to be influenced by the electrical resistance of the wires themselves.

This problem can be solved in two ways:

1. Use wires of the same length inside the structure, then the error arising from resistance and inadvertently introduced into the measuring circuit will be known in advance and can be compensated for at the signal input to the analog-to-digital converter;

IMPORTANT: On the weighing device "MASSA-K" of the "VT" series, "know-how" was applied, and the converter was installed directly on the sensor, which made it possible to do without wires and to solve the issue of resistance. However, at the engineering level, a miscalculation was made, namely: the calibration toggle switch remained not moved beyond the boundaries of the load cell, which led to the complication of testing procedures.

2. It is necessary to supplement the measuring circuit to check the resistance of the wire for a voltage drop and to dynamically correct the error from the resistance, which is introduced into the measuring circuit.

Load cell holes and their functionality

If there were no these holes, then the total load would be distributed over the entire surface to an equal degree, and, accordingly, it would be more difficult to establish the deformation. Due to the fact that the resistors are placed in the places where the highest voltage is concentrated, the place of integration of the latter is specially made thin so that the load applied to the edge of the beam would be expressed to the maximum in these places. Thus, the orientation of the resistors is relative to the thinnest point.

Strain gauge connection: shielding and grounding issues

An important issue in creating a successful and accurate weighing system using load cells is the organization of shielding and grounding. A competent solution to such a problem is the key to the correct functioning of a strain gauge device in the field of generating low-current signals. At the same time, the cables of the devices must have a shielding braid that would protect them from electrostatics and other interference, provided it is correctly installed.

The main and inviolable rule in this case should be the principle of avoiding "earthen" loops, which means the need to ground the device at a SINGLE and COMMON point. If you connect the cable shield at both ends, then a loop is inevitable. Thus, if the sensor body is reliably connected and properly fixed to the screen, then this will be enough, otherwise it is possible to connect the screen to ground only from ONE end, for example, in the electrical panel. It is worth remembering that it is highly discouraged to use "neutral" as a "ground electrode".

In the event that the sensors are connected in parallel, then you must not forget and connect the shield cable braids to each other, by means of the accompanying terminal contact in the junction box. After connecting, immediately "ground" them simultaneously with the body of the box itself.

Also, on ONE side, it is necessary to connect to the ground a common cable passing from the device to the junction box, while the formation of a "ground" loop must not be allowed. It is preferable to implement this scheme from the side of the receiver, i.e., near the entrance to the measuring device.

Directly on top of the insulation of the sensor cable (approximately at a distance of 4-5 cm from the equipment terminal), it is necessary to snap on the ferrite filter in order to block various interference on the ground. These filters are produced for cables of various sizes and diameters. They can also be installed on other extended lines, for example RS-485, both on the transmitting and receiving devices. Sometimes it may happen that the inductance of a single filter may not be enough. Then you will need to additionally and consistently click the filters at some distance from each other. This will raise the inductance to the desired level and reliably reduce the noise level.

Competent approach to the choice of load cells

Due to the fact that strain gauge devices are not particularly complex in their design, it is better to focus on the price when buying, and not on the manufacturer. Thus, although today's market is full of various price and brand offerings, there is no big difference between economy class and premium class.Expensive sensors should be purchased only when they are really needed for high-precision measurements, for example, in the food industry or for laboratory experiments. Otherwise, this purchase will not require large costs and will cost quite a standard price relative to standard measurement errors.

Regarding the Asian manufacturer of the products in question. As the analysis shows, the measurement accuracy of sensors from Taiwan, China, Korea is in no way inferior to the most popular companies. However, the material of their manufacture is often not durable and it so happens that the deformation of the beam on Chinese devices is visible with the naked eye immediately after carrying out a couple of several measuring procedures.

Rating of the best strain gauges for 2024

Budget options

3rd place: "CAS BSA-1"

The model is designed for use in electronic scales in catering and grocery stores. It has an improved design, the analog-to-digital converter (ADC) is accessed through a single wire, which does not cause a difference in resistance. Rather regarded as a spare part.

Name	Index
Manufacturer country	South Korea
Constructive type	Cantilevered
Weight, kg	0.23
Dimensions, mm	190x58x53
Price, rubles	2100

• Small dimensions;
• Increased accuracy;
• Connection to ADC with one cable.

• Narrow application focus.

2nd place: "100kg-3T"

Multifunctional sample of S-shaped design. It can be used in various types of scales designed for medium loads. Easy to install, can be paired with other sensors. Stranded wire provides a stable connection to the ADC.

Name	Index
Manufacturer country	China
Constructive type	S-shaped
Weight, kg	1.5
Dimensions, mm	94x86x35
Price, rubles	3800

• Multifunctionality;
• Acceptable price;
• Application based on average loads (from 1 to 3 tons).

• The resistor is likely to be fragile.

1st place: "Sierra SL6D-C3-10kg"

This sensor is designed for weighing packaging and other bulk products, not designed for a heavy load. Extremely easy to install and made of durable alloy steel for extended service life. Additionally, it has a dust and moisture protection class (as a separate item of weighing equipment).

Name	Index
Manufacturer country	Russia
Constructive type	Single point
Weight, kg	1.3
Dimensions, mm	130x25x22
Price, rubles	5600

• Optimal equipment;
• Advanced security features;
• Extended warranty (1 year instead of 0.5).

• Limited operating temperature - up to +35 degrees Celsius.

Mid-range models

3rd place: "METTLER TOLEDO CZL312"

Alloy steel sensor with nickel plated surface. It has a predominantly industrial purpose and is used for medium and high loads (weighing concrete mass at a construction site, weighing hot asphalt when laying a roadway, etc.). It can work in both tension and compression.

Name	Index
Manufacturer country	Switzerland
Constructive type	S-shaped
Weight, kg	12
Dimensions, mm	150x100x98
Price, rubles	11100

• Excellent value for money;
• Versatility;
• Increased lifting capacity (up to 10 tons).

• Small safe excess of the permissible NPI norm (no more than 30%).

2nd place: "T-100A"

This device is intended for use on relatively large cargo platforms - from 80x80 cm, and can also be used in bunker and filling scales. It is an example of a one-point design, therefore it can only be used in a single version.

Name	Index
Manufacturer country	Russia
Constructive type	Single point
Weight, kg	5
Dimensions, mm	45x54x79
Price, rubles	16300

• Increased accuracy;
• Works great on large platforms;
• Aluminum alloy body.

• Short warranty period (up to six months).

1st place: "CAS WBK-20TС"

Professional measuring device designed to check the weight of cars and various special equipment. It can be used at stationary traffic police posts to determine the permissible weight of vehicles for travel, as well as at customs posts.

Name	Index
Manufacturer country	South Korea
Constructive type	Cantilevered
Weight, kg	7
Dimensions, mm	85x70x95
Price, rubles	17600

• Manufacturing material - stainless steel;
• High lifting capacity (20 tons);
• Has its own moisture protection.

• Narrow specialization.

Premium class

3rd place: "T-50 (1st modification)"

The resilient design of this sensor allows for accurate readings even when a load is placed at the edge of the platform. The body tightness is ensured by the installation of special helium gaskets. The set includes a protective sleeve, cover and caps. The device is designed to work accurately with almost any weight - from small values ​​to extra large ones.

Name	Index
Manufacturer country	Russia
Constructive type	Single point
Weight, kg	8.1
Dimensions, mm	76x79x95
Price, rubles	33500

• Versatility;
• Good staffing;
• Operating temperature range from -40 to +50 degrees Celsius.

• Not found (for its segment).

2nd place: "CAS WBK-30-D"

The model is intended for industrial use, for example, for weighing bulk and liquid materials of large volume on enlarged platforms (determination of the weight of prepared concrete in a concrete plant). Easy to calibrate, stainless steel housing.

Name	Index
Manufacturer country	South Korea
Constructive type	Single point
Weight, kg	15
Dimensions, mm	84x83x45
Price, rubles	57000

• Robust body;
• Increased carrying capacity (up to 30 tons);
• Own moisture and dust protection.

• High price.

1st place: "LSU-100"

The low profile circular transducer is capable of handling ultra-heavy loads up to 100 tons. At the same time, the model has a reserve of additional NPI of about 150%. It can function in both compression and tension. The design uses a 4-core cable with a polyurethane protective braid, which guarantees high linearity and accuracy of data transmitted to the ADC. The system has its own moisture and dust protection, mounted in accordance with European standards.

Name	Index
Manufacturer country	South Korea
Constructive type	"washer"
Weight, kg	30
Dimensions, mm	307x278x90
Price, rubles	70000

• Increased resistance to wear;
• Ability to handle heavy loads;
• Actual price.

• Limited operating temperature at the lower limit (up to -10 degrees Celsius)

Conclusion

In order to save money, it is possible to order and purchase tensometry through the Internet sites. The popularity of this method is also due to the fact that it is very convenient to search for the desired model according to the specified parameters on the websites of sellers and manufacturers. It should be separately noted that, unlike retail, prices on the Internet will be much lower. Moreover, if a wholesale supply of a large amount of goods is required (for example, to provide an industrial facility), then a branded specialized store may well provide a discount. In addition, sensors are a commodity that is hardly possible to spoil even in conditions of extremely careless shipment, so there is nothing to be afraid of.