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Elevator failure analysis

Ningbo Beto Electric Co.,Ltd | Updated: Oct 27, 2016

Safety circuit
To ensure that the elevator can safely run, in the elevator is equipped with many safety components. Only if each of the safety components are in the normal case, the elevator in order to run, otherwise elevator stops immediately.
So-called security loop, is in the elevator safety components are equipped with a safety switch, all the safety switches series, control a safety relay. Only if all the safety switches are connected to the case, safety relays, and elevators to get running.
Common safety circuit switching are:
Room: a control screen emergency stop switch, phase sequence relays, thermal relays, limit switches
Shaft: upper limit switch, lower limit switch (lift both switches in safety circuits, while others use the switches control power supply directly)
Pit: rope maintenance box emergency stop switch protection switch, pits, buffer switching
Car: control box emergency stop switch
Sedan: safety safety clamp switch, window switch, car top inspection box emergency stop switch
Failure status:
When the lift is in the stopped state, all the signals cannot be registered and express local train were unable to run, first suspected safety circuit failure. Should be to the engine room control panel to observe safety relay status. If the safety relay is released, it should be judged as safety circuit failure.
Fault possible causes:
1. input power phase sequence of errors or missing due to the phase sequence relay.
2. lift long overrun or locked rotor, causing thermal relay.
3. may be caused speed limit speeding switch for velocity limiter action.
4. lift top or bottom causing limit switch.
5. pit rope switch. May be the speed limiter rope jump or long.
6. safety gear. The reasons should be identified. May be speeding action for speed limits, speed limiter missing oil malfunction, hang rope to hang rope pulley wheel loses oil, foreign body (such as mice) involved in the clearance is too small, safe lease blocks.
7. security being the top of the window, causing security window switching.
8. possible emergency stop switch was pressed.
9. If the switch is functioning, should check whether the contact is good, the wiring is loose.
In addition, more normal elevator safety circuit, safety relay also absorbs, but usually take a safety relay normally open contact and then sent to the computer (or PC) for testing, if the safety relay is bad, can also cause safety circuit failure State.

Lock loops
In order to ensure the elevator must be sector-wide shut down in order to run, in every office door and car doors are equipped with electrical interlock switches. Only sector-wide electrical interlock switches on all connected cases, control panel door lock relay to pull-in, elevators in order to run.
Failure status:
Sector-wide shut down state, observing the State of door lock relays to control screen, if the door lock relay is released, you should judge for the door lock circuit disconnect.
Repair method:
Since most express train will not run when the elevator door disconnect, so door lock fault is easy to determine, it is difficult to find out which door failure.
Maintenance recommendation:
1. first focus should be wondered whether the elevator stop layer door lock fault.
2. asked whether there is a triangle key to open the door, in the triangular key again switches the Office doors for external use of the Office.
3. ensure that in a State of repair, in the separate control panel short Office locks and lock the Office and out is the hall door parts car door parts failures.
4. If door parts failures, ensure that the maintenance condition, short Hall door lock circuit, repair speed lift, check each layer by layer daoting interlock contacts (don't forget the passive door).
Note: after you fix the door lock circuit failure, short must first take off the door lock wiring, can restore the lift to fast track status.
In addition, greater lift door lock circuit properly, door lock relays also absorbs, but usually take a door lock relay normally open contact and then sent to the computer (or PC) for testing, if the door lock relay is bad, can also cause door lock circuit failure State.

Safety edge (photoelectric, door Ray)
Elevator doors are caught in the shutdown process to prevent passengers, it is generally in the elevator door is provided with a safety edge (or optical or light curtains).
Safety edge: mechanical type clamp device, when in the process of closing, one safety edge is encountered, safety edge indented inwards, driven lower by a micro-switch, safety edge switch, control door to door direction.
Optical: elevator door photo (at least two), while the transmitter and receiver on the other side. When the elevator doors closed, if an object blocks out the light receiver transmitter light cannot be accepted immediately driven optical relay, photoelectric relays control the door opened to the opposite direction.
Screen: same principle as the optical, but there are many transmitting and receiving points.
Failure status:
1. the elevator door will not shut
Phenomenon: the elevator cannot close automatically, or left then back open. Can slam in their maintenance.
Safety edge switch is bad or stuck, switch or were improper, safety edge action that caused the switch action a little bit.
Door Ray (or screen) position or occlusion. Or optical without (light curtain) power supply, or electronic devices (screen) is bad.
Secure the touch pad does not work
Safety edge switch bad or the wire has been broken.
Identify reasons to repair.

Closing limit switch
Elevator door closing force limit switch when the door is in the process of closing if certain resistance but still won't shut the door, then the switch, the door to door directions.
Although some variable frequency crane without this switch, but has a similar function. If there is some resistance in the closed, through the calculation of frequency converter door cannot be closed when current exceeds a certain value, to the opening in the opposite direction.
Failure status:
When the action is wrong when the closing limit switch is always not shut the door.

Open-Close button
Automatic position, if you press and hold the Open button, the elevator doors opened for a long time, passengers much normal in and out of the car.
Click the close button, you can make the doors closed immediately.
Maintenance when used to control the elevator doors.
Sometimes got stuck in the door button is pressed inside play out. If stuck Open button may cause the lift at the station door open not shut up. Close button is stuck cause arriving back door does not open.
Identify the cause, keep the buttons, flexible and reliable.

Hall call button
Hall call button is used for passengers call the registration office needs. Meanwhile, it has the function of the door in the same direction. When the elevator to move, hold the call on down, the elevator doors opened for a long time. (Some elevators are designed to be a certain amount of time after compulsory closing).
Sometimes called elevator will stop when the button is stuck closed on this layer. Or run over a period of time after the force had closed, and then sailed to the each layer to stay for some time.
Identify the cause, keep the buttons, flexible and reliable.