Technical Glossary

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There are currently 28 Terms in this directory
Maintained actuation
Also designated byalternateor ON / OFF

Position of the switch which remains unchanged when the operating force ceases to be exerted on the operating member of the switch. Contrast with Momentary.

Momentary actuation
Temporary position after which the switch returns to its normal position.

Capacitive load
Electrical load in which the initial current when the contact closes is higher than the permanent current.

Inductive load
Electrical load in which the initial current on contact closure is lower than the permanent current and the opening current is higher than the permanent current. The stored energy causes a long and intense electric arc.

resistive load
Electrical load in which current and voltage are in phase.

Metallic surfaces that come into physical contact to create an electrical circuit. These surfaces are on the moving contacts and the outputs.

NC contact
The NC contact (forNormally Closed) designates a "Normally Closed" (NC) contact, ie at rest the circuit is closed, the contact between the two poles is established.


Contact NO
An NO contact is a "Normally Open" contact (orNormally Open), that is to say that at rest the circuit is open, the contact between the two poles is not established.

NONC contact
(Normally Open and Normally Closed)

Acronym used to designate a contact that can be both Normally Open and Normally Closed. Also defined by the acronym NONF.

The NO/NC buttons have many interests:

  • Functional: a classic switch has an input and an output. It can be NO (Normally Open) or NC (Normally Closed). A switch with a NONC function has one input and 2 outputs, with consequently 2 possible actions. One default action when idle and a second action when activated.

  • Safe / redundancy function: A NONF switch also offers a redundancy function. It is used to check the correct operation of the system and therefore of the device on which it is mounted.

Rated current
Maximum current that can flow through the already closed contacts of a switch.

Total distance that the operating device can perform.

Touch effect
AlsoTactile feedback.

Switching sensation felt by the operator of the switch interface. Defined by the strength of the audible “Click” that indicates movement of the contact.

Form A
Form A refers to a contact configuration term.

Form A refers to a SPSP normally open contact. "1 Form A" means there is one Form A contact in the module, "2 Form A" means there are two "Form A contacts" in the module, and so on.

The form A contact can be schematized according to

Form B
Form B refers to a normally closed SPST contact arrangement. This means that it stays in a closed (off) state without you driving the relay to operate. "1 Form B" means there is one "Form B contact", "2 Form B" means there are two "Form B contacts" in the relay, and so on.

The form B contact can be schematized according to

Form C
Form C refers to a single-pole-double-throw (SPDT) contact. This means that there is a common point connected to one normally open end and another normally closed contact. "2 Form C" refers to two "Form C contacts", and so on.

The form C contact can be schematized according to

Form X or dual contacts are equivalent to two Form A contacts in series, mechanically linked and actuated by a single actuator, and can also be described as SPST-NO contacts. They are commonly found in contactors and toggle switches designed to handle high power inductive loads.

Form Z or double break contacts are comparable to Form C contacts, but they almost always have four external connections, two for the normally open path and two for the normally closed path.

The form Z contact can be schematized according to

Impact Rating
Impact resistance (FR)

Protection sign
Ingress Protection

Alongside the criteria of robustness, resistance to shocks, vibrations and high temperatures, there is a determining variable, that of the IP protection index. Regardless of the sector of activity (industrial, medical, aeronautics, transport, etc.), each piece of equipment must be protected against the intrusion of solid bodies and liquids.

The Ingress Protection (IP) rating is an international standard from the International Electrotechnical Commission relating to waterproofing. This index classifies the level of protection offered by a material against the intrusion of solid and liquid bodies. The format of the index, given by the IEC 60529 standard, is IPXY where the letters XY are two digits and/or a letter. The numbers indicate compliance with the conditions summarized in the tables below. When no criteria are met, the number can be replaced by the letter 9.

The piezoelectric effect (from the Greek “Piezein”, to press, to press) was discovered in 1881 by the Curie brothers.

This is the property of certain bodies (such as quartz, topaz, ceramics, certain crystals and polymers) to become electrically polarized under the action of a deforming force (direct effect); reciprocally to deform when an electric field is applied to them (Indirect effect).

Number of separate circuits that can be activated by a switch at one time. A single pole switch allows only one closed circuit. A bipolar switch allows two closed circuits...

breaking capacity
The ability to switch (switch) an electric charge. The load can be capacitive, resistive or inductive. Opposes nominal current.

Contact bounce
Also calledbouncing contact

Switching period during which electrical instability caused by the physical bouncing of contacts is observed. The relative mass of the contacts, their mechanics, the forces and frequencies of the bearing elements determine the intensity of the rebound.

Impact resistance
Impact Rating

Since 1995, the IK resistance index has become a specific index measuring the mechanical resistance of a product to impacts. It is attached to the European standard EN 62-262.

The IK index is rated on a scale of 0 to 10, depending on the impact energy, which can range from 0 to 20 joules. For example, a device displaying an IK05 index withstands shocks of 0.70 J, in other words, it withstands the fall of a mass of 350 kg from a height of 20 cm. According to the standards, the minimum IK of a device takes into account its place of installation. For example, appliances located in kitchens must have a minimum IK02. The IK index is measured using a specific test, carried out using a “Sharpy sheep” (figure below).

Sharpy sheep
Sharpy sheep

Insulation resistance
Electrical resistance between two normally insulated parts, measured at a given DC voltage.

contact resistance
Electrical resistance between two closed contacts.

Dielectric strength
Ability of an insulator to withstand a voltage without the formation of an electric arc on its surface. This is the standard voltage that can be applied between two open outputs or between an output and ground without causing a short circuit.

Part of the switch, external to the body, which is used to connect it to an electrical circuit. Example: solder lug, wire lug, screw lug, etc.