Application: The ultrasonic position system USP uses a non-contact operating principle to position lift cabins. This principle is not based on conventional switching technology or common encoder systems and the USP is cost-efficient because of its simple design. This system is very technically advanced and is able to communicate with the very latest control systems.
Area of application Alongside mechanically operated limit switches, magnetic reed switches are enjoying an increase in importance. They are often used to complement limit switches with plungers, rollers and swivel levers and are considered an important link to non-contact and contactless limit switches. In lift construction, magnetic reed switches are used to generate zone signals, levelling signals, delay points and to generally determine positions. These are used preferably where mechanically actuated limit switches no longer function satisfactorily due to unfavourable operating conditions such as high or low startup speeds, high switching frequencies, strong dust or dirt influence, high humidity, or large fluctuations in operation interval, or where noise emission must be avoided.
The magnetic reed switches consist of two units, the switch and the actuating magnet. The contacts of the switch are protected from dust, humidity and corrosion through the enclosed glass tube. Magnetic reed switches thus have an extraordinarily high contact reliability. The enclosures are made of thermoplastic; the versions for the different applications are rectangular, cylindrical or flat. Magnetic reed switches are fitted with mounting holes, threaded bolts, screwed flanges or on C-rails. They are provided with a central fixing screw or slotted holes for the adjustment. BN 260 is highly insensitive to transverse misalignment.
Design and operating principle There are normally open (NO), normally closed (NC) and bistable contacts; with some types, the switching conditions are indicated by LED. The switches are actuated with actuating magnets with and without enclosure. Depending on the type of switch, a specific actuating magnet for lateral or front actuation as well as different actuating distances can be chosen. In order to avoid malfunctions, the actuating planes are provided with symbols. Because of their bias voltage, bistable contacts are the most sensitive switches. Depending on the application, magnetic reed switches with pre-wired cable, cable entry or connectors are available. Protection class is up to IP 67.
Area of application Position switches with safety function are suitable for a wide range of applications in lift industry. They are especially used, where safety and positioning accuracy are of paramount importance, e.g. at the terminus, at the safety catch device or at the speed limiter.
For these applications, Schmersal offers a comprehensive program of position switches, which have proven their value to the lift industry all over the world. The different series can be smoothly adapted to the specific application by means of a wide range of actuating elements.
All position switches with safety function have a positive link between the actuator and the positive break NC contact. The switches are available with two different switching systems: snap action (Z) and slow action (T). The protection class of all series is IP 54 up to IP 67. The metal or thermoplastic enclosures are available in two standard sizes. They have a good resistance to oil and petroleum spirit.
The user can choose from several combinations of NC and NO contacts. The switches are connected through screw terminals or plug-in connectors. The ZSM 241 with electrical reset is supplied with connecting cable. Some switches have an additional wiring compartment cover, which means that the contacts are never exposed, not even when the switch cover is opened. In this case, the cables can be smoothly connected by means of the cage clamps.
Area of application The door contacts with positive break of the AZ series are available in ten different versions so that a suitable contact for monitoring the door position or the locking mechanism (hook bar) is available for all types of elevators. They are tested and certified in accordance with the European and American standards.
Design With the AZ safety switches, the switching element and actuator are not connected to each other in terms of the design. However, when they are switched they are joined together functionally or separated. When the safety device is opened, the actuator is separated from the base device. In the process, the NC contact in the safety switch is opened through positive breaking.
Round or elongated holes serve to attach the switch; on some types, captive securing bolts are included in the scope of delivery.
Application: The lift door bolting devices (AV) are used to monitor and lock one- or two-leaf lift landing doors. The fail-safe interlocks comply with the 20/14/33/EU and the EN 81-1 lift directives.
There are versions with aluminium pressure cast housings and plastic housings, one or two locking elements either on the left or right, with lever, pull strap or attached brackets. The transparent cover means that the safety function can be monitored. The locking bolt has a 22 mm travel, which guarantees that the mandatory engagement depth of 16 mm is safely maintained after the lowering of the door. With a triangle key, the emergency release can be actuated from outside.
Operating principle of the certified locking device: The European Lift Standard EN 81-1 stipulates that: „It shall be impossible, from positions normally accessible to persons, to move a lift with the landing door open or unlocked after a single action, which is not part of the normal operating sequence.“ Our door locking devices with magnetic certified locking device of the AV 15, AV 20 and AV 25 type meet this requirement. They are therefore admitted for passenger lifts. They are therefore admitted for passenger lifts.