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Posted by on October 14, 2020

China Micro Switch Manufacturer has developed the safety switch with interlocking suitable, for example, for the electrical emergency stop of the traction system of an elevator in the event of excess speed.

The Unionwells series represents a range of safety switches perfectly adapted to the needs of the elevator sector, with a large number of units in service around the world. The pre-stroke of these switches is only 0.2mm.

These microswitches share the main basic elements of the ZS 231, although it is designed as a remote release latching position switch. After the switch is switched to the opposite end position, it locks. The release is carried out by means of a solenoid, which can remotely receive the electrical actuation signal, for example, from a button located on an external control panel. It is ideal for carrying out the electrical emergency stop of the traction system, which intervenes when the mechanical limiter located at the head of the well detects an excess speed in the elevator car. In this case, it is actuated by the centrifugal mechanism of the limiter, whose signal activates the engine brake, so that it is not necessary to activate the emergency brake of the cabin.

For safety reasons, the engine brake remains activated until the cause for the cab overspeed is located. Once the fault is detected, the safety switch is released. Since the limiter, which is specially adjusted and verified for each lift, works according to the centrifugal principle, the ZSM 241 has to work with maximum precision. This means that before the speed limiter is triggered, the brake has to act on the traction system.

This application makes a remote release system recommendable, since traction systems and with them also speed limiters are increasingly installed directly in the shaft, rather than separately in a machine room. In this way, direct access to the limiter is impossible. If the ZSM 241 safety switch is installed, it can be released simply through a button located on the control panel, thus avoiding risks for the operators and the lift’s service is restored earlier. That’s the speciality of China Micro Switch Company that produces such amazing microswitches.

Another application of the micro switches used in elevators can be the control of the emergency release by triangular key on the lower deck gate, in order to prevent an operator from being trapped inside the shaft: When unlocking the first deck door, the switch changes and, even if the door is closed, the elevator cannot be started until the operator has released using an external reset key. The extremely short maneuvering pre-stroke of the ZSM 241 ensures that it is activated with maximum reliability when the manual release is actuated.

For more on micro switches, contact unionwell at

Name: James Yuan


Organization: Huizhou Unionwell Technology Co., Ltd

Address: No. 532, Office Building, Huizhou Industrial Transfer Industrial Park, Longmen County, Huizhou City, Guangdong Province, China

Phone: +86- 18169936698

Posted in: Business, Services


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