Operating Environmental Interference and Countermeasures of Contactless Products

Compared with resistive potentiometers, the core of contactless potentiometers is electronic circuit of senors. The interference and impact of external electrical disturbances will impose some certain impact on it.

Contactless potentiometers (magnetic angular displacement or linear displacement sensor), as the upgrading products of resistive potentiometers, is increasingly widely used in the industrial control, instrument and apparatus, vehicles, ships and other fields.

Compared with resistive potentiometers, the core of contactless potentiometers is electronic circuit of senors. The interference and impact of external electrical disturbances will impose some certain impact on it.

01 Types and causes of electrical disturbances

Contactless potentiometers and joysticks, after connected to the user's control system, become a part of the system, whose working state is closely related to the whole system, will be affected by the electrical disturbance generated by the surrounding environment. These disturbances mainly come from both the power supply and signal output due to the peak voltage superimposed on the power line and electromagnetic interference through inter-wire coupling. These disturbances eventually act on the power supply and signal output ends of the contactless potentiometers in the form of voltage. Excessive shock voltage will lead to working instability or damage of contactless potentiometers.

02 Protection measures against electrical disturbances

To solve the interference problem, the key is to provide clean power supply for contactless potentiometers and to avoid inter-wire coupling between.

Providing independent power supply for the contactless potentiometers and separately wiring the strong and weak electricity, or installing power filter at the end of the contactless potentiometers, can effectively solve or reduce the interference effect.

For those customers that cannot be improved due to operating environment or system reasons, in order to ensure the safety of customers, Shanghai SIBO., relying on the experience of R&D and production of various kinds of contactless potentiometers (sensors) and joystick for decades, in combination with customers’ actual applications, design a systematic protection scheme, as a solution for customers to select and use.

Solution 1: Basic version

Recommended reasons:

- - -Overvoltage protection at the power supply end

- - -Voltage protection and output reverse current limiting protection at signal output end

Recommended Index: ★★★★

For example: WLH22E 0505, WLH22D 0505

For customers who use 5V power supply and output 0-5V, we provide the basic protection measures on the products. The product provides overvoltage protection at both the supply power and output signal ends, as well as reverse current limiting protection. When the power supply and signal output ends has too high peak voltage, the protection circuit will limit the voltage below the safe range, to protect the sensor.

This solution provides limited basic protection. If the the peak voltage amplitude is so high and lasts so long that exceed the capacity of the protective device, the product can still suffer irreversible damage. We recommend products with 24V power supply to the users who have such kind of problem, which will provide more comprehensive protection.

Solution 2: Enhanced version

Recommended reasons:

- - -Provide enhanced protection current solutions.

- - -Overvoltage protection, filtering, overcurrent protection, internal stable voltage regulator circuit elements at the power supply end.

- - -Overvoltage protection and output reverse current limiting protection at signal output ends.

Recommended Index:★★★★☆

For example: R40 2442，JH30

For the products of power supply 12-30V, output 0-5V/0-10V, we provide the enhanced circuit protection solutions. The enhanced protection version of the products added overcurrent and overvoltage protection, filtering, current limiting, internal stable voltage regulation and other measures to protect the power supply end and signal output end of the products. Compared to the basic protection version, the enhanced version can provide protection against continuous high voltage shocks. For the 4-20mA output products, we provide the same protection at the power supply end.

Solution 3: Ultimate version

Recommended reasons:

- - -External protection module.

- - -Overvoltage protection, filter overcurrent protection, internal stable voltage regulator circuit at the power supply end.

- - -Overvoltage protection and output reverse current limiting protection at signal output end

- - -Enhanced filter absorption circuit.

Recommended Index：★★★★★

Protection module SBP040SIBO can be used with contactless products (potentiometers, joysticks) from SIBO.

The environmental electrical disturbance is very strong. If the product's electrical disturbance of working environment is very strong, the product in

Solution 2 cannot meet the situation, we provide the external protection module scheme. The scheme provides overvoltage protection, filtering, overcurrent protection, internal sensor stable voltage regulator circuit, and internal signal amplification circuit at the power supply end, and provides overvoltage protection and output end reverse current limiting protection at the signal output end.

Compared with the Plan 2, the filter absorption circuit is enhanced in this plan, so that the sensor has a stronger ability to maintain normal operation under the impact of external disturbance. The protection circuit of power supply and signal output ends exists is an independent module, which can be replaced separately once damaged. This plan is more suitable for external protection and power supply module of contactless joystick, which is used for engineering vehicles under bad working conditions.

Traditional potentiometers and contactless potentiometers, as a branch of sensors, have more or less interference problems in application.

Our customers have encountered some manufacturers clamouring that the contactless products have interference and cannot be used, not knowing that this reveals their lack of technical ability and their helplessness in the face of interference.

SIBO, as a professional manufacturer of R&D and production of potentiometers, joysticks and derivative equipments, has a rich experience in the application of anti-interference, able to provide different solutions according to customers’ operating environment. At the same time, SIBO has traditional precision potentiometers, contactless potentiometers, magnetic encoders, joysticks, various kinds of conversion and anti-interference modules, from different aspects and different angles, to provide customers with integrated solutions.