How can sound and light alarms be integrated with elevator control systems to prevent false triggering or missed alarms?
Publish Time: 2025-10-28
Sound and light alarms play a crucial role in the safety and protection of modern elevator systems, especially when the elevator enters bypass mode. During this period, the elevator's conventional safety circuits may be partially or completely bypassed, suspending normal operation and posing a significant safety risk. To ensure the safety of personnel working in the hoistway and prevent accidents such as pinching and crushing caused by unexpected car movement, the sound and light alarm installed at the bottom of the car must be able to issue timely and accurate warning signals. The key to achieving this goal lies in deep integration of the sound and light alarm system with the elevator control system, ensuring that the alarm is triggered at the correct time and eliminating false and missed alarms.1. Signal Linkage: Automatic Triggering Mechanism Based on Operating ModeSound and light alarms do not operate independently; rather, they are part of the elevator's safety control system, connected to the main control board or safety relay module via hardwiring or a communication bus. Their triggering logic is directly derived from the elevator's operating status signals. When the operator uses a dedicated key or button to switch the elevator to "Maintenance Mode," "Bypass Mode," or "Emergency Run Mode," the control system outputs a specific dry contact signal or communication command, automatically activating the sound and light alarm at the bottom of the car. This "mode linkage" mechanism ensures that the alarm is only activated during abnormal operating conditions, preventing false alarms during normal passenger operation that could disturb passengers or cause panic.2. Multiple Input Judgment: Preventing False TriggersTo prevent false alarms caused by single-signal interference or erroneous operation, modern elevator control systems typically employ a multi-condition judgment strategy. For example, alarm activation depends not only on the "maintenance switch" signal but also on multiple conditions, such as "door lock circuit disconnected," "safety clamp inoperative," and "car not in level position." Only when all pre-set safety conditions are met does the system deem it a "legal maintenance operation" and trigger the alarm. Furthermore, the control system filters and delays the input signal to prevent false triggering due to transient voltage fluctuations or poor contact.3. Fault Self-Detection and Status Feedback: Eliminate Missed AlarmsMissed alarms are more dangerous than false alarms and can lead maintenance personnel to encounter a moving elevator car without warning. Therefore, the sound and light alarm system must feature real-time self-detection and status feedback. The control system regularly sends test signals to the alarm to verify the proper functioning of its speaker and flashing light. If a circuit break, a damaged lamp, or a power failure is detected, the system immediately issues a fault code to the control cabinet or monitoring terminal and may lock the elevator until the alarm is repaired. Some high-end systems also support two-way communication, allowing the alarm to proactively report its status, achieving closed-loop monitoring.4. Power Supply and Circuit Independence: Ensuring ReliabilitySound and light alarms are typically powered by an independent circuit from the elevator control power supply. Some systems also include a backup battery to ensure that even in the event of a main power outage or a power outage in the control cabinet, they can still emit a brief sound and light signal, providing a final safety alert. Furthermore, the alarm signal line uses shielded cable to prevent electromagnetic interference from affecting signal transmission. The control and safety circuits are physically isolated but logically closely linked, ensuring both independence and interconnectedness.5. Optimized Installation Location and Signal PropagationThe alarm is installed at the bottom of the car, facing the shaft, ensuring that the sound and light propagate vertically downward, covering the pit and lower shaft areas. The flashlight utilizes a high-brightness LED with a flashing frequency that meets international safety standards, ensuring detection even in darkness or when visually obstructed. The sound output is no less than 85 decibels, providing strong penetration and effective transmission within the complex shaft structure.In summary, through deep integration with the elevator control system, the sound and light alarm signal utilizes technical features such as mode linkage, multiple judgments, self-test feedback, and independent power supply, achieving a highly reliable, low false alarm rate, and zero missed alarms. It serves not only as a "guardian beacon" for elevator maintenance but also as an integral component of the smart elevator safety system, providing a solid line of defense for shaft workers.
