Compare prices by matching the right specifications

When assessing the price of an inductive sensor, consider its housing size, sensing distance, output type and operating environment together. Define the features you need before comparing models in the inductive sensor category. Two sensors that look alike may not be electrically interchangeable.

Features that affect the price

Inductive sensing uses the interaction between a metal target and the alternating magnetic field generated by a coil. Common switching models indicate whether a metal object is present or absent. Applications requiring continuous distance measurement need a suitable model with a measurement output.

Housing diameter and length: A short or miniature sensor that fits a confined machine space need not cost the same as a model requiring more installation room. A smaller housing does not always mean a lower price, and a larger housing does not always mean a higher one. Thread length, mounting nuts and cable exit direction also affect mechanical compatibility.

Sensing distance and target material: A value specified for steel can differ with aluminium, stainless steel or a smaller target. Extended-range designs and special sensors offering similar distances across different metals should not be compared with a standard model without considering these differences. With flush and non-flush sensors, account for the required clearance from surrounding metal.

Outputs and additional functions: A single switching output, complementary outputs, analogue measurement and IO-Link communication serve different needs. Some IO-Link models allow their switching point and output function to be configured. Assess the cost of an additional feature against the configuration or diagnostic benefit it brings to the application.

Three wires, four wires and output compatibility

The choice of PNP or NPN must match the receiving input circuit. NO and NC describe the output function when the target is detected and are separate from the PNP/NPN distinction. A matching supply voltage alone does not make two products interchangeable.

A four-wire model may provide two separate outputs, while another may use the additional conductor for a different function. Consequently, there is no fixed price difference between three-wire and four-wire sensors. For two-wire sensors, also check leakage current, minimum load and on-state voltage drop. Read the wiring diagram and check input compatibility before drawing conclusions from the wire count.

Total cost of cabled and connector versions

For a cabled sensor, compare cable length and jacket material. For a connector version, check whether the required sensor cordset and connector are included in the price. Pin count, pin assignment and straight or angled connections must suit the installation. The price of the sensor alone may differ from the total cost of a working connection.

Why can a low-cost model be unsuitable for a fast application?

For conveyor counting or monitoring a rotating metal target, assess the required counting frequency alongside switching frequency and response time. PLC input filtering and the method used to read the signal also affect the result. Use a high-speed counter input where required. A sensor detecting the target does not by itself establish that the controller can capture every pulse.

Environmental suitability and standards

The IP protection rating, temperature range, chemical exposure, vibration and cable movement require separate checks. An IP67 marking, for example, does not establish resistance to oil, coolant or every chemical. The housing, sensing face and cable jacket must suit the actual operating environment.

Inductive sensor standards and manufacturer documentation support comparison of ratings, connections and application limits. A standard detection sensor cannot be selected for personnel protection solely because it carries a standard reference. Assess the relevant product suitability separately where a special environment or safety function is involved.

An example of comparing replacement sensors and prices

Suppose the existing product is an M18, 24 V DC, PNP NO sensor with an integral cable. A second product carrying those descriptions can still differ in sensing distance, flush mounting capability, housing length and output current. Compare the metal target, operating temperature and cable requirements as well. Housing diameter and a PNP NO description alone do not complete a replacement assessment.

Assessing current prices

Compare prices using the complete product code and equivalent order conditions. Check the currency, VAT treatment, quantity, stock status, lead time and included accessories stated on the product page or quotation. Quotations from different dates or with different connection accessories are not directly comparable without allowing for those differences.

Model groups and related categories

Models by housing: miniature inductive sensors, M12 inductive sensors, M18 inductive sensors, M30 inductive sensors and rectangular inductive sensors.

Further sensor categories: cylindrical inductive sensors, two-wire inductive sensors and NAMUR models and all sensor groups.

Categories that complete the application: PLCs, power supplies, counters and relays form part of the system connected to the sensor. Where continuous position or speed information is required, encoders can also be assessed against the application’s needs.