ESW- 7 :- Safety Devices / Components

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Elevator, Escalator & MovingWalk

Elevator Safety @ Safety Devices / Components 

Safeties In Elevator: 

Equipment Protections

• Over load
• Voltage fluctuations
•  Over speed
•  Phase reversal
• Phase failure

Safety Devices / Components in Elevators

S.N	Safety	Function
1	OSG and Safety Gear	To prevent free fall of an elevator in down direction Designed to operate when the speed exceeds 110% of actual Breaks safety circuit and thereby stops motor when actuates Instantaneous or Progressive
2	Safety gear in counterweight (not common)	To prevent free fall of counterweight Designed to operate when the speed exceeds 110% of actual Breaks safety circuit
3	Buffers	Stops the car / CWT when over travels (Spring or oil) Designed to absorb the impact Terminal limit switch breaks the safety circuit
4	Car door lock	Operates on 230VAC Car moves only when the contact is closed Mechanical lock is provided for special cases
5	Electro-mechanical lock for landing doors	Locks the landing door when shuts and makes electrical contact(230VAC) Prevent opening from outside Opens only when car reaches the landing Possible to open from outside with emergency key
6	Electrical lock for landing doors	Shorting piece located in the other door panel Makes electrical contact when the door shuts(230VAC)
7	Pressure Limiter	Senses pressure exceeding certain value during door closure and prevents the door closure.
8	Earthing	To prevent shock hazard All components are earthed as per requirement
9	Pit switch	Located in pit, 1 or 2 switches Breaks the safety circuit when switched ON(230VAC)
10	Counterweight guard	To prevent the weights from falling outside the frame when a cwt buffers
11	Intercom	Operates with separate inverter supply(24VDC) Passengers can communicate outside(where receiver unit kept)  when they are trapped inside the car
12	Emergency alarm	Operates with separate inverter supply(24VDC) To seek help from outside when passengers are trapped inside the car
13	Emergency light	Operates with separate inverter supply(230VAC)
14	Photo cell	Additional safety to prevent the doors from closing if anybody is in-between the doors
16	Car stop switch	Switch provided in the Car operating panel (COP)(230VAC) On pressing stops the lift immediately.
16	Rescue Device	Emergency rescue devices Operates during power failure and system failure Brings the lift to the nearest floor and opens the door Provides supply to motor using maintenance free batteries
17	Synchronization switch	Provided at the extremes of the shaft (near to deceleration lvl) Decelerates the elevator and updates the position when operates
18	Stop limit switch	Located at extremes of the shaft apprx.30mm away from floor Stops the elevator in one direction when operates Meant for service personnel safety
19	Final Limit switch	Located at extremes of the shaft after the stop limit switch Breaks the safety circuit when operates Operated before the car buffers
20	Light Curtain	Infra-red light curtain door safety helps to sense passenger movement on automatic door elevators. As soon as it senses movement or obstruction the doors go back and keeps it open. It helps to prevent accidental collisions and jamming of elevator doors.