1. SAPB (Single Automatic Push Button Control):
This forms the simplest type of control system. In this system, all floors have only one hall button. The buttons may or may not have telltale lights (TTL) to indicate call registration. At a time only one call will be attended. The control system does not register calls while running. It attends to the first person who presses the hall button after completing a travel. This type of arrangement is used only in single speed elevators with low cost applications.
2. Down Collective Control:
For this system, all floor have DOWN hall buttons only except the ground floor where there is UP hall button only. If there are basements, Ground floor will have both UP and DOWN hall buttons and the basement have UP hall Button. The operation is similar to Simplex and Duplex controls. Since there are only down hall buttons all the calls are serviced sequentially during the down travel of the elevator. These types are most suitable for residences and small hotels where inter floor traffic is very rare. This type of arrangement not only reduces cost but also reduces unnecessary waiting time in residential elevators.
3. Simplex Full Collective Control:
This is a fully automatic operation used for a single elevator system. Hall fixtures have two buttons, one for UP travel and the other for DOWN travel. If our intended direction of travel is in up direction, UP button has to be pressed and if our intended direction of travel is in down direction, the DOWN button has to be pressed. In acknowledgement to our pressing of the button, a light inside the button glows and this is called a telltale light. Hall calls in the direction in which the elevator is traveling are responded sequentially and when calls in that direction are cleared, calls in the opposite direction will be responded to. When there are no more calls, the elevator will stay on the last attended floor level. In some cases, the free car is moved to ground floor where the arrival of passengers is more frequent. With the advent of microprocessor technology, parking of free car at any predetermined desired floor possible.
4. Duplex Collective Control:
This a fully automatic operation used for two elevator systems. Hall fixtures have two buttons, one for UP travel and the other for DOWN travel. If there are buttons for each elevator, as in simplex control, it is called two Riser arrangements. Most common type of arrangement of hall buttons is of one riser, meaning, one set of UP and DOWN buttons at each floor common to both the elevators. This type of arrangement saves cos. The operation is similar to simplex except that the calls are shared by both the elevators and hall calls are responded to by whichever elevator that can serve the hall call faster. In this type of arrangement, both the elevators share a common machine room and the elevators are located adjacent to each other.
5. Group Control:
This is a group control system used to operate a bank of three or more elevators, normally limited to six though it is not uncommon to see eight elevators in a group. The elevators share a common machine room and are located near each other. The numbers of risers have to be decided based on the location of elevators and convenience of the users.
Typical Arrangement of Control System:
1. Description of Control System in an Elevator:
In actual practice, the arrangement of electronic assemblies and their inter communication vary from manufacturer to manufacturer. However a general popular arrangement of electronic assembles and their inter communication has been described in the above picture and below paragraph.
1.1 Main Controller:
The main controller is the heart of the elevator system. Initial controllers were designed using electro mechanical relays but most of the controllers manufactured today use micro-processors. The controllers have two parts namely logic control and the motion control. Basic operation of logic controllers is to receive signals from car or hall buttons and decide the direction of motion based on its own position. The command to move is transferred to the motion control which in the current designs is the ACVF drives. ACVF drives provide a smooth start, control the speed of the main machine and stops the elevator without jerk. The ACVF elevator drives are smart devices to control the motion and provide a smooth ride to the passengers inside the elevator. Smooth speed control is achieved due to the closed loop feedback provided by the encoder mounted on motor shaft. Switches mounted in the hoist-way provide the door zone, limit and floor position signals. As the car moves, the floor position signals are counted by the logic controller to update its position.
1.2 Hall Button & Position Indicator:
This panel which is mounted in each floor, near the hoist-way door, has an UP button, a DOWN button and an optional position indicator. The UP button must be pressed, if one wants to go up. Similarly the Down button must be pressed, if one wants to travel down.
In general all the Hall buttons are connected serially to the Processor board in the machine room. Whenever a button is pressed, it is communicated to the master processor in the controller. It is also common to note that in low rise buildings, the hall buttons are discretely wired to the master control unit. Communicating serially or in parallel is a commercial decision, however nowadays most of the elevators operate on serial communication. In general, the hall fixtures communicate with the master controller either in RS485, CAN or RS422 communication protocol.
Riser: Each floor has a Hall Button and Position Indicator. This vertical arrangement of HB assembly is called a Riser.
1.3 Hall Lanterns & Gong:
Hall Lanterns and gong are optional fixtures opted in multiple car group to announce the arrival of an elevator to a particular landing and its subsequent direction of travel. These fixtures also communicate with the master controller and get the commands.
HALL LANTERN & GONG
1.4 Car Operating Panel (COP):
The calls can get registered from the car operating panel also. Whenever a call is registered, it is immediately acknowledged by the controller by lighting the call button, which is termed as tell-tale light. The tell-tale light feature is available in hall buttons also.
1.5 Movement of Elevator:
On entering the lobby of any building, one finds elevators; single, two or multiple cars in the lobby. There are fixtures with UP and DN buttons. The UP button is to be pressed if one intends to travel in up direction. Similarly, the DN button is required to be pressed if the intended travel direction is DOWN.
A part from the Hall button fixture, one may also notice visual indicating displays showing the actual location of the lift at that time and the direction of travel. The controller decides the direction of ravel and commands the ACVF drive accordingly. The ACVF drive endures the speed and ride quality such as acceleration and jerks.
In some lift lobbies, the hall fixture may have only one button. The control system in this case is called Down Collective Control (DCL). The elevator stops to the called hall button, only during its down ward travel.
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