The 110 VAC / 24 VDC light curtain protects the door opening by detecting people or objects. Here you will see what specific symptoms indicate that a qualified technician should inspect or replace the unit. We use simple terms and focus on why each warning sign matters for safety and elevator operation.
›››What is this light curtain and why does it matter
It is an optical barrier for automatic doors that covers 2000 mm in height and features 174 beams to detect presence in the door opening. It has a response time of 100 ms and operates with 110V input, plus provides 24 VDC power supply.
Detecting failures in a light curtain is key because its function is to prevent the door panel from closing on a person or object. If it fails, the safety of users and the operational compliance of the elevator are compromised.
- 174 beams along 2000 mm for vertical detection.
- Response time of 100 ms for quick reaction.
- Includes transmitter, receiver, cables and installation kit.
›››Warning Sign 1: The door does not reopen when an obstacle is detected
What it means: The door should reopen when the light curtain detects an object or person in the opening. If that does not happen, the unit may have lost its detection capability or the signal between transmitter and receiver may not reach the door system.
Why it matters: A light curtain that does not trigger preventive opening leaves users exposed to door closing, which represents a clear risk of entrapment or equipment damage. Additionally, the failure may indicate an electrical or communication problem that affects other door control elements.
- Possible beam failure or TX–RX synchronization issue.
- Interruption of 24 VDC supply or problem in control box.
- Direct risk to user safety.
›››Warning Sign 2: The door does not close or reopens without reason (erratic detection)
What it means: If the door stops or reopens with no obstacle present, the light curtain may be generating false alarms. Erratic detection shows up as intermittent signals or continuous blocking with no apparent cause.
Why it matters: False triggers cause unnecessary cycles, wear door mechanisms and create inconvenience for users. They also prevent normal elevator use and may lead to emergency interventions by personnel.
- Possible causes: dirt on the beams, incorrect receiver alignment, or internal electronic failures.
- Causes higher power consumption and wear on the automatic door.
- Need for professional diagnosis to avoid unnecessary replacements.
›››What a qualified technician will do
The technician must check alignment and cleanliness of transmitter and receiver, verify electrical connections (including 110V power and 24 VDC lines) and test the light curtain response. He or she will also check the physical integrity of the aluminum profile and included control unit.
If after tests the light curtain does not perform its detection function or shows intermittent failures, the technician will recommend repair or replacement with a unit that maintains door safety.
- Inspection of transmitter (TX) and receiver (RX).
- Verification of power and signal to the control box.
- Functional tests under real operating conditions.
›››Frequently asked questions
Can I clean the light curtain myself?
You can clean the outer profile surface with a dry or slightly damp cloth, but any electrical testing or adjustment should be left to a qualified technician.
Does the light curtain work in extreme climates?
The unit operates in a temperature range of -20°C to +65°C, which allows it to function in cold and hot environments within that range.
What does the spare part include when installed?
The light curtain includes transmitter (TX), receiver (RX), cables and installation kit; there is also a control box option available.
If you detect any of these warning signs, ask a qualified technician to inspect the light curtain. Among the spare parts we are most frequently asked for is the Light Curtain 110 VAC / 24 VDC 2.0 m; a professional diagnosis will help you decide whether repair is enough or replacement is recommended. Request a quote or write to a store advisor to receive personalized assistance.