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Trouble shooting measures for subway screen doors

Date:Sep 01, 2020

Trouble shooting measures for subway screen doors


(1) The platform unit controller (PEDC) of the screen door malfunctions

   1. The sliding door on the whole side cannot be opened or closed

   Failure analysis: Signal ATC cannot open or close the sliding door on the whole side. Due to the omission in the control logic circuit design of the manufacturer PEDC, the entire side sliding door cannot be closed. PEDC is composed of power board, logic control circuit board, safety relay, aviation plug, etc. It has been confirmed that there is no quality or installation problem with power board, safety relay, aviation plug, etc.

   Treatment measures: restart the PEDC or replace the PEDC, return the faulty PEDC to the factory for repair, but the PEDC still frequently fails after the repair.

  2, ISCS displays "PEDC failure", but does not affect the opening and closing of the door

Failure analysis: When this failure occurs, the local control box (LCB) and local control panel (PSL) can open and close the screen door, ISCS reports "PEDC failure", and the PEDC failure display of ISCS changes from green to red. The monitoring device (PSA) also has a fault history display.

   Treatment measures: If this fault occurs, the PEDC can be restarted by cutting off the control power supply. Because the Westinghouse PEDC equipment is unstable, it can be temporarily treated by percussion vibration. If the above method cannot be recovered, the PEDC should be replaced.

  3, ISCS displays "PEDC channel failure", but does not affect the opening and closing of the door

   Failure analysis: The channel failure indicator flashes, and ISCS reports the channel failure. The reason is that PEDC's single-chip microcomputer malfunctions.

   Treatment measures: Power off the PEDC and restart it. If it still cannot be recovered, it proves that the internal microcontroller is damaged, and the PEDC should be replaced in time.

  4, ISCS displays "CanBus failure", but does not affect the opening and closing of the door

  Fault analysis: The data bus plug is loose, affecting the communication between the door controller (DCU) and PEDC.

   Treatment measures: check the data bus plugs one by one, mainly check the PL7 plug, insert it firmly and tighten it.

   (2) Safety circuit failure and treatment

1. Analysis and treatment of safety circuit failure caused by the travel switch. The travel switch of the sliding door and emergency door enters the safety circuit. Each time the sliding door is opened and closed, the travel switch must be activated. It operates from 5 to 24 every day During the time, the train passes approximately 280 times, so the 4 travel switches in the locking mechanism must operate 280 times a day. In operation, the contact of the travel switch is on and off due to vibration, but the screen door DCU does not have the function of monitoring the contact of the travel switch entering the safety circuit. When the safety circuit is disconnected and the failure occurs, the LCB switch can be used to switch each sliding door Open the door manually and observe the "close and lock" indicator light of PSL. If the indicator light of a sliding door is on, it indicates that the travel switch of the sliding door has malfunctioned. However, because this kind of failure occurs randomly, the door body vibration causes the travel switch to vibrate, sometimes prompting the contacts to return to normal. In addition, when the operation peaks, the driving interval is short, and the time is not enough to check the entire side of the 24 sliding doors. It often happens without inspection. Several sliding doors, the next time the train enters the station, the vibration of the sliding door switch action restores the travel switch contacts to normal. In view of the above failures, the travel switch needs to be checked regularly. A multimeter can be used to block power, the test lead is connected to the normally open contact of the travel switch, and the roller is moved with the thumb. The resistance should be 0 or less than 0.1Ω after the roller is moved. If the resistance is infinite after the roller is moved, the stroke should be replaced. switch. Aiming at the short duration of safety circuit failure and the characteristics of recovery after door action or vibration, a signal opening and closing simulation device has been developed. After the operation is stopped at night, the platform screen door signal is used to command the simulation device to repeatedly open and close the sliding door. When the safety circuit is not connected after the sliding door is closed, it stops sending the door open and close commands.

  2. Analysis and treatment of safety circuit failures caused by DCU main board and connectors. DCU main board is installed in each sliding door machine. The power supply of the safety circuit is DC 60V, which is sent to the main board of the sliding door operator that is the farthest from the screen door equipment room. After the normally open contacts of 120 travel switches are connected in series, this voltage is sent to the PSC slave in the screen door equipment room. The safety relay coil of the relay unit, the slave relay unit sends a "close and lock" command to the ATC device. During use, it was found that the PL14 and PL15 connectors on the main board were sometimes loose or individual pins were loose, causing the safety circuit to be disconnected. When a failure occurred, ISCS and PSA did not have any record of the failure door. If the fixing screw of the travel switch is loose or improper adjustment of the travel switch can cause all sliding doors and emergency doors to be closed and locked, the safety circuit is low. The pins should be tightened, all plugs should be reinstalled if necessary, and the travel switch should be adjusted to ensure that the safety circuit works normally.

   (3) Insulation failure of the screen door

   1. Analysis of insulation failure of screen door

   The top and bottom of the screen door structure are insulated and installed, and insulation tape is laid on the edge of the platform under the decoration layer of the platform to achieve insulation between the door and the ground, and to avoid damage to the human body caused by step voltage. As the decoration ceiling lamp belt touches the upper cover of the screen door, the insulation of the door is damaged.

   2. Treatment measures

In order to avoid the insulation problem of the screen door from affecting the safety of the car, an insulating film can be used to paste the insulation film on the metal part of the screen door to ensure the safety of passengers and prevent the electric shock caused by touching the live shell of the screen door (post and door frame) when getting on and off passengers .

   (4) Drive power failure

  1, ATC can't be used for uplink and downlink signals

Fault analysis: PDP has no 380V AC output due to drive power failure, power supply unit 380V/39.4V of single door has no current output, DCU is not in operation, therefore, single door LCB mode switch cannot open sliding door, priority 5 Only the triangular key can be used to open the door manually. The remaining LCB, integrated backup control panel (IBP), PSL, and signal opening are all invalid. Because the DCU cannot work, the door status indicator is off. After this failure occurs, use a multimeter to check whether the +3―Q1 and +5―Q1 in the PDP cabinet are energized, check the feed-in and feed-out voltages of the drive UPS and bypass cabinet, check the working position and voltage of the ATS, and check the drive The working status and fault indication of the PK module of the UPS.

   Treatment measures: The ATS should be restored immediately. If the ATS is damaged, the bypass air switch should be manually closed to restore the power supply. The electromechanical personnel should take care of the site and replace the ATS after the shutdown.

  2, the single-block rectifier and inverter power module of the drive power UPS fails and exits work. A total of 9 power modules are installed in the PK rack, and a certain power module often fails to exit work and give an alarm.

Failure analysis: The manufacturer’s equipment has certain defects. Its inverter process is operated in parallel through several inverters. Unlike the DC power supply, AC power supplies can be directly connected in parallel. The inverters must be connected in parallel with the same frequency and phase. When the specifications are met, the initial phase angle of the output is inconsistent, causing the current to circulate internally, or even circulating current in severe cases.


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