Technical terms and keywords

What exactly is a 'nominal sensing range'? What does 'correction factor' mean? You will find an overview of technical terms related to sensor technology together with concise and clear explanations. Save yourself a laborious search and simply read it up here. You will find more detailed information in our specialist knowledge area – benefit from our know-how!


Determination of the switching function of the signal output. E.g. NO (normally open) or NC (normally closed).
Background suppression
Distance range within which diffuse reflection sensors and optical distance sensors do not detect objects in the beam path (behind the object to be registered).
The sensing face of the sensor may engage flush with the metal installation environment, but it may also go beyond it.
Assured sensing range Sa
The assured sensing range (Sa), also known as the operating sensing range, takes the effects of supply voltage, temperature and sample scatter on the sensor's sensing range into account. Between 0% and 81% of the nominal sensing range, reliable switching with standard target is guaranteed under all permissible operating conditions. Sa <= 0.81 of the nominal sensing range Sn.
Complete protection against contact with electrically conducting parts. Protection against ingress of dust, protection against water jets.
Complete protection against contact with electrically conducting parts. Protection against ingress of dust, protection on immersion in water under defined conditions: 1 m depth of water and 30 minutes duration.
Complete protection against contact with electrically conducting parts. Protection against ingress of dust, protection on immersion in water under defined conditions: 1 m depth of water and 7 days duration.
Complete protection against contact with electrically conducting parts. Protection against ingress of dust, protection against water during high-pressure / steam jet cleaning; specifically for road vehicles. Also a marking for use in the foodstuffs and pharmaceutical industries.
If the material of the damping object for the sensor differs from that of the standard target, sensing ranges arise that differ from the sensor's real sensing range Sr. They can be calculated with the aid of correction factors that are given in the technical data. Example: Nominal sensing range 20 mm, real sensing range 19.6 mm, correction factor (metal) for aluminium 0.4: This means that the current real sensing range to this material is 19.6 mm x 0.4 = 7.8 mm.
The nominal sensing range describes the maximum distance a standard target may be removed from the sensor such that the sensor can still switch. It does not take production tolerances, temperatures or voltage fluctuations into account and therefore represents a theoretical value. It is also known as the 'rated sensing range'. A standard target is made of the material ST37 (mild steel), it is square and has a side length of 3 times Sn or the diameter of the sensing face, whichever is the greater. It is flat and even and one millimetre thick.
The sensing face of the sensor may on no account lie flush with the metal installation environment.
Polarity of the signal output – switching direction. The switching direction points towards plus. The minus or zero potential of the supply voltage is switched by the signal output. A characteristic of the NPN technology is that the load is permanently associated with plus. The opposite case is termed PNP switching.
points towards minus. The plus potential of the supply voltage is switched by the signal output. A characteristic of the PNP technology is that the load is permanently associated with minus. The opposite case is termed NPN switching.
90% to 110% of the nominal sensing range
The sensing range is the physical displacement at which a metallic measurement plate approaching the sensing face triggers a signal change at the output. The signal output remains switched within the sensing range.
The switching frequency refers to the maximum number of binary switch-on and switch-off signal output operations per second. Ideally, the switch-off time is twice the length of the switch-on time.
A switching function of a binary signal output. If a sensory event occurs in the active range, the switching signal changes from 'Off', 'Low' or '0 volts' to 'On', 'High' or to the operating voltage (e.g. 24 VDC).
The protection rating is an indication of the suitability of electrical equipment for a range of environmental conditions, as well as the degree of protection for people using it with regard to potential hazards. Protection ratings are determined according to DIN 40 050. Protection ratings are indicated by means of internationally valid abbreviations (IP = International Protection (marking)). The abbreviation IP is followed by two digits as well as two additional letters if required. The first digit indicates the degree of protection against the ingress of solid bodies. The second digit indicates the degree of protection against the ingress of water at room temperature.
The protection classes are designed for the categorization and marking of electrical equipment. They provide information regarding the safety measures in place to prevent electric shock. There are four protection classes: 0, I, II, III. Equipment is marked with the aid of symbols.
Protection class III equipment operates with so-called SELV, which stands for 'Safety Extra Low Voltage'. This means that no special protection is required. Protection class II devices have enhanced or even duplicated insulation to the housing. Protection class I is the protective earth (yellow-green connection wire).