What is a seismic sensor in an elevator?

The elevator seismic sensor (also known as Elevator Seismic Switch/Seismic Detector/Earthquake Detector) is designed to work in conjunction with an elevator control system, ensuring the elevator enters a controlled operational mode before or during an earthquake.

How does the elevator seismic sensor work?

When an earthquake is detected, the system senses seismic waves in advance and outputs an alarm signal to the elevator control system. This triggers the elevator to stop at the nearest floor, open its doors, and allow passengers to exit safely. By doing so, it maximizes passenger safety and minimizes potential damage to elevator equipment.

What Types of Seismic Sensors are used in elevators?

Elevator seismic control systems typically utilize two types of seismic sensors:

Mechanical Seismic Sensors: These consist of a magnet, sensing element, and micro-switch. When the sensing element detects vibrations exceeding a preset threshold, it triggers the micro-switch to send an output signal. These sensors are widely used in Japan due to their mature technology and reliability.

Electronic Seismic Sensors: Commonly used in the U.S. and Europe, these sensors utilize high-sensitivity, low-noise three-axis MEMS accelerometers. The accelerometers measure seismic acceleration and generate corresponding electrical signals. These signals are filtered and processed by a high-precision analog-to-digital converter, which then sends data to a microprocessor. The microprocessor analyzes the data, determines seismic activity, and outputs control signals accordingly while recording the event.

What are the main components of an elevator earthquake detector control system?

The elevator earthquake detector control system consists of several key modules:

Processing Unit: Analyzes seismic data and controls the system’s response.

Acceleration Sensing Module: Uses a three-axis accelerometer to detect ground motion in the X, Y, and Z directions.

Reset and Testing Circuit: Ensures proper functionality and system reliability.

Power Supply Module: Provides stable energy for continuous operation.

Clock Module: Records seismic events with accurate timestamps.

Contact Output Module: Triggers emergency control actions.

Storage Module: Logs earthquake occurrences and system responses.

The system operates by detecting P-waves (primary waves) and S-waves (secondary waves):

P-waves are the initial vertical ground vibrations that an earthquake produces. The accelerometer detects these vibrations, processes the signal, and sends an alert.

S-waves follow P-waves and cause stronger horizontal shaking. The system detects and processes these waves to determine the earthquake’s severity and respond accordingly.

Where elevator earthquake seismic sensors are installed?

Elevator seismic detection systems are typically installed in the machine room or at the top of the elevator shaft, ensuring effective communication with the control system. The installation location must meet the following criteria:

1.Close to the control system: Allows for immediate transmission of emergency stop commands.

2.Free from obstructions and mechanical interference: Ensures accurate seismic wave detection.

In earthquake-prone regions such as Japan and the U.S., seismic sensors are often integrated near elevator control systems. Common installation methods include:

Shaft top installation: Directly monitors elevator movement and external vibrations.

Machine room installation: Positioned near the control cabinet for fast response and signal transmission.

By incorporating a seismic detection and alarm system, elevators can swiftly enter emergency operation mode, preventing accidents and safeguarding passenger lives during seismic events