BY : TME
Vandal, specialised components and complementary products.
The switches, which are resistant to various environmental conditions and mechanical impacts, are used in devices intended to be placed in public spaces (lifts, ticket machines, etc.), but also in industrial machines, vehicles and many other installations.
Below is an overview of solutions from the ONPOW brand, whose range is filled with high-quality electromechanical components, primarily resistant switches with increased durability. Their design solutions meet the needs of modern installations – control panels or human-machine interfaces (HMI). We invite you to take a look at our offer.
In this article we cover topics such as:
- General characteristics of the most resistant switches
- The use of the piezo effect
- Overview of standard push button switches
- Typical applications of rotary switches
- Key-operated switches
- Components with acoustic signals
Vandal resistant push buttons
Although the name ‘vandal resistant switches’ would suggest that these are products that are immune to intentional attempts at destruction – in fact their most important feature is simply durability, long life and resistance to a range of factors – not only impacts but also harsh environmental conditions, dust, flooding etc. In fact, they are buttons with a robust design that protects them from damage, both intentional and accidental, and above all from ordinary but long or irresponsible use. Others offer almost two thousand different solutions in this area.
“Vandal resistant” ONPOW buttons are made almost exclusively as panel-mounted components, with a threaded body (stainless steel or aluminium) – this design makes it virtually impossible to remove the switch from the face. Depending on the model, the mounting hole used to seat the button can range from 12mm to 40mm in diameter, which also gives an approximate idea of the size of the keys. Others are available with LED backlighting in various colours, appearing as dot, ring or symbol.
In terms of electrical performance, it is worth noting that among the range on display were switches suitable for standard, low DC voltages (e.g. up to 24V DC), but also capable of operating in mains circuits (250V AC). Contacts were placed in SPST, SPDT, DPDT configurations. The range includes mono and bistable versions, and therefore, among others, versions that can act as switches. Thanks to the variety of models in the ONPOW range, manufacturers of devices intended for use in public spaces (ticket machines, lifts), as well as industrial machines or control panels placed in ships, heavy machinery etc. will find interesting items.
Switch terminals are usually flat connectors or solder contacts. In selected cases, ONPOW models have screw terminals or factory pre-installed cables. From the installer’s or manufacturer’s point of view, a worthy solution will be versions equipped with a terminal quick connect (and compatible contact blocks) – these allow easy replacement of the switch, whose leads have a fixed configuration and are placed in a standardised holder.
In addition, ONPOW also supplies other accessories associated with vandal resistant switches, e.g. stoppers or guards.
Piezoelectric switches
Unlike the switches described above, piezoelectric switches have no moving parts or gaps. This type of pushbutton uses – as the name suggests – the piezoelectric phenomenon, i.e. the generation of a voltage by pressure. This means that the body of the component is completely free of gaps (from the face) and the mechanical resistance here is very high, directly related to the strength of the monolithic aluminium body. The situation is slightly different for illuminated switches, but they too are characterised by unrivalled service life (50 million cycles). Buttons of this type are only available in monostable versions, in diameters from 16mm to 22mm, suitable for voltages 5V, 12V or 24V DC.
The face of a piezoelectric switch is quite smooth and gap-free.
Toggle switches
The end of the lever can take the shape of a sphere or the base of a cone.
ONPOW also supplies toggle switches in a format similar to vandal resistant switches (also panel mounted, 16mm diameter opening). These are capable of switching conductive circuits up to 5A at 250V AC. It is worth noting that these products also contain illuminating elements (rings around the joints of the clamping levers). The design ensures IP67 protection level.
Standard push button switches
When building control panels, control panels or other machine interfaces, very high protection class and mechanical strength are not always required. For applications where the standard tightness (IP40) is sufficient, ONPOW offers many types of pushbuttons, in a wide variety of colours. Although it should be noted that also in this group you can find elements with characteristics IP65. The manufacturer has prepared illuminated, mono and bistable variants, with the shape of the button round, square or rectangular, with concave, flat and convex faces.
Switches are available with contacts in configurations SPST, SPDT, DPDT. They can handle DC and AC circuits (up to 20A in mains-powered applications). They are adapted to operate in temperatures from -25°C to 55°C. For typical applications (e.g. appliance switches) there are versions with standard symbols on the front of the key.
Rotary switches
Rotary switches are a special type of electromechanical component – they are used where the risk of accidental switching must be minimised. Often, as in the case of ONPOW products, they offer more than 2 stable positions. The range also includes illuminated versions (red and green), for insertion into holes with diameters of 16mm or 19mm.
Models available from the ONPOW range support mains voltages and currents up to 3A. While they can therefore be used for direct switching of small loads – they are better suited as signal elements, controlling machines and circuits indirectly. An interesting item in the supplier’s range are rotary switches made entirely of metal (stainless steel), and therefore resistant to many environmental and chemical factors.
Rotary switches of the “ignition switch” type
A special type of rotary switches are versions equipped with a lock, whose position cannot be changed without inserting a key into the slot. This is an additional protection against unauthorised access to certain machine functions, circuits, installations (e.g. defrosting, tank draining). Such switches are available in sizes (diameters) from 16mm to 30mm, in 2 and 3 position versions (also monostable), with a removable key in each position.
Even the ignition switches come in illuminated versions (although not all of them). Another differentiating feature of these is the rotation angle, which is 45° or 90°. In some versions, the key and body have been additionally coated with plastic. Independently of this, the insulation of the switches has been tested with a voltage of 1.5kV, while their electrical life is estimated at min. 50,000 cycles.
Sound signalling devices
Against the backdrop of others switches, sound signalling devices are the standout item in the ONPOW range – but it is important to note that they have been designed to harmonise aesthetically (as well as technically) with vandal resistant switches. Like them, they have been made in the form of panel-mounted, threaded bodies.
Selected sounders offer IP67 protection and high mechanical resistance. They emit a well audible signal (e.g. at 2.3kHz) with a volume of 75dB to 85dB (depending on the model), steady or intermittent. ONPOW offers versions powered by DC voltages (12V, 24V) as well as mains (220V AC).
Text prepared by Transfer Multisort Elektronik Sp. z o.o.
