EP3216735A1

EP3216735A1 - Pulsed opening of elevator brake enabling passenger evacuation

Info

Publication number: EP3216735A1
Application number: EP16159692.9A
Authority: EP
Inventors: Amit BHOR
Original assignee: Inventio AG
Current assignee: Inventio AG
Priority date: 2016-03-10
Filing date: 2016-03-10
Publication date: 2017-09-13

Abstract

An apparatus and method for use during a power disruption to open the elevator brakes enabling the evacuation of passengers trapped in an elevator car. The apparatus comprises at least one flywheel diode (62) configured for anti-parallel arrangement with an output of the pulse electric brake opening device (PEBO). The flywheel diode (62) eliminates back EMF from the brake coil (34) permits continued circulation of current in the brake coil (34). Accordingly, on each electric pulse from the pulse electric brake opening device (PEBO) the jerk experienced by passengers within the car (4) during the manual evacuation procedure is reduced considerably but also the actual time taken to evacuate the passengers is also greatly reduced.

Description

The present invention relates to elevators and, more particularly, to an apparatus and method for use during for a power outage to open the elevator brakes so as to permit the imbalance of mass between the elevator car and the counterweight to move the elevator to the nearest landing so that any passengers within the elevator car can be evacuated.
A conventional traction elevator typically comprises a car, a counterweight and traction means such as a rope, cable or belt interconnecting the car and the counterweight. The traction means passes around and engages with a traction sheave which is driven by a motor. The motor and the traction sheave rotate concurrently to drive the traction means, and thereby the interconnected car and counterweight, along an elevator hoistway. At least one brake is employed in association with the motor or the traction sheave to stop the elevator and to keep the elevator stationary within the hoistway. A controller supervises movement of the elevator in response to travel requests or calls input by passengers.
The brakes must satisfy strict regulations. For example, both European Standard EN 81-1:1998 and the ASME A17.1-2000 code in the United States state that the elevator brake must be capable of stopping the motor when the elevator car is travelling downward at rated speed and with the rated load plus 25 %.
Furthermore, the elevator brake is typically installed in two sets so that if one of the brake sets is in anyway faulty, the other brake set still develops sufficient braking force to slow down an elevator car travelling at rated speed and with rated load.
Conventionally, the elevator brakes engage with a rotating component of the motor such as a brake drum or brake discs mounted for concurrent rotation of the motor shaft. Each brake normally has a brake pad that is spring biased towards the surface of the brake drum or disc. Additionally, an electromagnet may be arranged within the brake so that when the coil of the electromagnet is energised it exerts a force on the brake pad to counteract the spring bias and release or disengage the brake pad from the brake drum or disc.
Accordingly, the brake is released or disengaged by supplying electricity to the brake coil through a power supply circuit. Conversely, the brake is engaged by disconnecting the power supply circuit from the brake coil for example with a relay or contactor arranged within the circuit.
When a complete power failure or a disruption such as under-voltage occurs with the commercial mains power supply, the brake pad immediately engages to brake the movement of the elevator car. In these situations, it may be necessary to evacuate any passengers trapped in the elevator car. Conventionally, a pulse electric brake opening device (PEBO) typically housed in a control cabinet at one of the landings of the installation, can be activated so that a series of electrical pulses are supplied to the brake coils from a mains-independent power supply. On each such electrical pulse, the brakes are opened and the car can move under the gravitational influence of the imbalance between the mass of the car and that of the counterweight. This procedure can be repeated until the elevator car comes into alignment with a landing, at which point the landing and car doors can be opened and the passengers can alight.
During this manual evacuation procedure, the elevator car will be stopped and started multiple times resulting in considerable jerk which will be uncomfortable and unsettling to any passenger riding in the elevator car and, in some cases, might even lead to injury of the travelling passenger. This problem is understandably further exaggerated in countries throughout the world which experience frequent power disruptions.
An objective of the present invention is to solve the aforementioned drawback by providing an apparatus and method for pulsed opening of the elevator brake to enable passenger evacuation during power disruption.
Accordingly, the invention provides an adapter configured to be inserted across at least one output of a pulse electric brake opening device used during power disruption to open at least one elevator brake, the adapter comprising at least one flywheel diode configured for anti-parallel arrangement with an output of the pulse electric brake opening device.
The purpose of the flywheel diode is to eliminate back EMF from the brake coil and to continue circulation of current in the brake coil when each electrical pulse from the pulse electric brake opening device ends.
The adapter can be easily fitted or connected to an existing pulse electric brake opening device and provides the benefit that not only is the jerk experienced by passengers during the manual evacuation procedure reduced considerably but also the actual time taken to evacuate the passengers is also greatly reduced.
Furthermore, since fewer pulses are required from the pulse electric brake opening device for the evacuation trips using the adapter, the lifespan of the pulse electric brake opening device itself is increased and additionally there is significantly less energy consumption.
Preferably the adapter further comprises at least one flywheel diode configured in anti-parallel with all outputs of the pulse electric brake opening device.
Typically the adapter is configured to be inserted into an interface of the pulse electric brake opening device. Conventional pulse electric brake opening devices generally already include such an interface to allow maintenance and commissioning engineers to diagnose and test the elevator brakes. Accordingly, there is no requirement to modify or reconfigure the hardware of the opening device.
The invention also provides a combination of the adapter described above in combination with a pulse electric brake opening device.
The pulse electric brake opening device may include a mains-independent power supply and a pulse generator. The term mains-independent power supply is intended to mean that the power supply is available even when the commercial mains AC power supply has been disrupted. It may be one or more batteries which in turn can be recharged from the commercial mains AC power supply when available. As fewer pulses are required from the opening device for the evacuation trips using the adapter, there is significantly less energy consumption from the mains-independent power supply.
Optionally, a converter can be provided between the mains-independent power supply and the pulse generator to buck or boost the voltage from the battery to that required by the pulse generator.
Preferably, the pulse electric brake opening device further comprises a manual evacuation switch configured to selectively connect the pulse generator to one or more elevator brake coils. Accordingly, the opening device is inactive and disconnected from the brake coils during normal operating conditions when the commercial mains power supply is available and is only brought into action by the manual evacuation switch when required.
Furthermore, a manual evacuation button maybe configured to selectively connect the pulse generator to the mains-independent power supply. Each press of the manual evacuation button will activate the generator to supply a short series of electrical pulses to the brake coils. On each such electrical pulse, the brakes are opened and the car can move under the gravitational influence of the imbalance between the mass of the car and that of the counterweight.
Typically the generator is configured such that each electrical pulse will have a duration of less 500ms and the interval between pulses in less that 2s.
The rescue personnel can repeatedly press the manual evacuation button until the elevator car comes into alignment with a landing. At this point, the rescue personnel can remove the adapter, go to the landing adjacent the car level, and manually open the doors to allow any passengers to exit from the car.
The invention not only provides for an adapter to connect to an existing pulse electric brake opening device as summarised above, but can be applied internally to the hardware on new pulse electric brake opening devices. Such a pulse electric brake opening device would be configured to open at least one elevator brake and would include a pulse generator and at least one flywheel diode arranged in anti-parallel with an output of the pulse generator. Again the arrangement provides the benefit that not only is the jerk experienced by passengers during the manual evacuation procedure reduced considerably but also the actual time taken to evacuate the passengers is also greatly reduced.
Furthermore, since fewer pulses are required from the pulse electric brake opening device for the evacuation trips using the adapter, the lifespan of the pulse electric brake opening device itself is increased and additionally there is significantly less energy consumption.
Typically, the pulse electric brake opening device will comprises at least one flywheel diode arranged in anti-parallel with each output of the pulse generator.
Again, the pulse electric brake opening device will typically include a manual evacuation switch to selectively connect the pulse generator to one or more brake coils and a manual evacuation button to selectively connect the pulse generator to a mains-independent power supply.
The invention also provided a method for evacuating elevator passengers trapped in an elevator car during power disruption. The method comprises the steps of providing at least one flywheel diode in anti-parallel with a coil of an elevator brake and providing one or more electrical pulses to the coil. On each such electrical pulse, the brakes are opened and the car can move under the gravitational influence of the imbalance between the mass of the car and that of the counterweight.
This method provides the benefit that not only is the jerk experienced by passengers during the manual evacuation procedure reduced considerably but also the actual time taken to evacuate the passengers is also greatly reduced.
Typically, rescue personnel will repeatedly pulse the coil until the elevator car comes into alignment with a landing.
At this point, the rescue personnel can go to the landing adjacent the car level and manually open the doors to allow any passengers to exit from the car.
Preferably, the elevator is disconnected from the commercial mains AC power supply for the manual evacuation procedure.
The novel features and method steps characteristic of the invention are set out in the claims below. The invention itself, however, as well as other features and advantages thereof, are best understood by reference to the detailed description, which follows, when read in conjunction with the accompanying drawings, wherein:

FIG. 1 is a schematic illustration of a typical elevator installation;
FIG. 2 is a schematic of the main components of the electro-mechanical brakes of FIG. 1;
FIG. 3 is a topography illustrating the brake controller of FIGS. 1 and 2 in combination with a conventional pulse electric brake opening device;
FIG. 4 is a graphical representation of output from the pulse generator of FIG. 3
FIG. 5 is a graphical representation of jerk measured within the elevator car during the pulsed operation of the brakes illustrated in FIG. 4;
FIG. 6 is a topography illustrating a pulse electric brake opening device according to an embodiment of the present invention;
FIG. 7 is a graphical representation of jerk measured within the elevator car during the pulsed operation of the brakes by the pulse electric brake opening device illustrated in FIG. 6;
FIG. 8 is a topography illustrating a pulse electric brake opening device according to a further embodiment of the present invention;
FIG. 9 is a graphical representation of jerk measured within the elevator car during the pulsed operation of the brakes by the pulse electric brake opening device illustrated in FIG. 8;
FIG. 10 is a topography illustrating a pulse electric brake opening device according to a further embodiment of the present invention; and
FIG. 11 is a flowchart illustrating the method steps for evacuating passengers trapped in an elevator car during power disruption.

A conventional elevator installation 1 for use with the method and apparatus according to the invention is shown in FIG. 1. The installation 1 is generally defined by a hoistway bound by walls within a building wherein a counterweight 2 and car 4 are movable in opposing directions along guide rails. Suitable traction means 6, such as a rope or belt, supports and interconnects the counterweight 2 and the car 4. In the present embodiment the weight of the counterweight 2 is equal to the weight of the car 4 plus 40% of the rated load which can be accommodated within the car 4. The traction means 6 is fastened at one end to the counterweight 2, passed over a traction sheave 8 located in the upper region of the hoistway and fastened to the elevator car 4 at the other end. Naturally, the skilled person will easily appreciate other roping arrangements are equally possible and that the counterweight balancing factor can be changed as required to meet particular specifications.
The traction sheave 8 is driven via a drive shaft by a motor 12 and braked by at least one elevator brake 14,16. The use of at least two brake sets is compulsory in most jurisdictions (see, for example, European Standard EN81-1:1998 12.4.2.1). Accordingly, the present example utilises two independent, electro- mechanical brakes 14 and 16 to engage with a disc mounted to the drive shaft of the motor 12. As an alternative to the brake discs, the brakes could be arranged to act on a brake drum mounted for concurrent rotation with the drive shaft of the motor 14 as in WO-A2-2007/094777 . The structure and operation of the brakes 14,16 will be described in more detail in the description below of FIGS. 2-6.
Conventionally, power from the commercial mains AC power supply is fed through the contacts of a main power switch JH in three phases L1, L2 and L3 via a frequency converter drive FC to the motor 12. The drive FC includes a diode-bridge rectifier 20 which converts AC line voltage into DC voltage on a DC link 22 which would typically include a capacitor to smooth any ripple in the DC voltage output from the rectifier 20. The filtered DC voltage of the DC link 22 is then input to an inverter 24 and converted into AC voltages for the motor 12 by selective operation of a plurality of solid-state switching devices within the inverter 24, such as IGBTs, which are controlled by PWM signals output from a motor controller MC incorporated in the drive FC.
Overall operation of the elevator 1 is controlled and regulated by an elevator controller EC. The elevator controller EC receives calls placed by passengers on operating panels located on the landings of the building and, optionally, on a panel mounted within the elevator car 4. It will determine the desired elevator trip requirements and, before commencement of the trip, will instruct a brake controller 40 within the drive FC to output a current signal I so as to release the brakes 14,16, and additionally issue a travel command signal C to the motor controller MC which energises and controls the inverter 24 to allow the motor 12 to transport the passengers with the car 4 to the desired destination within the building. Movement of the motor 12, and thereby the elevator car 4, is continually monitored by an encoder 22 mounted on the traction sheave 8 or on the motor shaft. A signal V from the encoder 22 is fed back to the motor control MC permitting it to determine travel parameters of the car 4 such as position, speed and acceleration.
Although the brake controller 40 is shown in FIG. 1 as being incorporated within the drive FC, it will be readily appreciated that the brake controller 40 can be housed separately and external to the drive FC or even contained within the elevator controller EC.
FIG. 2 is a schematic illustrating the main components of the electro- mechanical brakes 14 and 16 of FIG. 1. Each brake 14;16 is connected by suitable cabling to a brake controller 40 and includes an actuator 30 and an armature 36 to which a brake lining 38 is mounted.
The actuator 30 houses one or more compression springs 32 which are arranged to bias the armature 36 in brake closing direction C towards a brake disc 24 mounted on a drive shaft of the motor 12. Additionally, a brake coil 34 is arranged within the actuator 30. The coil 34, when supplied by current I from the brake controller 40, exerts an electromagnetic force on the armature 36 in the brake opening direction O to counteract the biasing force of the springs 32 and move the armature 36 away from the brake disc 24.
FIG. 3 is a topography illustrating the brake controller 40 of FIGS. 1 and 2 in combination with a conventional pulse electric brake opening device (PEBO). In normal operation of the elevator 1, when sufficient mains power supply is available, DC power derived from the mains power supply, can be selectively supplied to the coil 34 through the brake contactor or relay BR as shown in schematic of the brake controller 40 of FIG. 3. Accordingly, in normal operation, the brakes 14;16 will be released by closing the brake relay BR such that current I flows from the positive terminal +V through the coils 34 of the brakes 14;16 to the ground terminal 0V. Conversely, when the brake relay BR is opened, the brake coils 34 are simultaneously disconnected and the compression springs 32 will move the armatures 36 in the direction C so that the brake linings 38 engage and thereby brakes the brake disc 24.
For convenience to the rescue personnel, the pulse electric brake opening device PEBO is typically housed at an accessible location such as in a control cabinet at one of the landings of the elevator installation. The pulse electric brake opening device PEBO includes a mains-independent power supply, in this case a battery 52, which can feed electrical power to a pulse generator 56. An optional converter 54 can be provided if the voltage rating of the battery 52 is significantly different to that of the pulse generator 56. The pulse generator 56 can in turn supply a series of electrical pulses to the brake 34 of each of the brakes 14,16. The pulse electric brake opening device PEBO will also include an interface 58 which allows maintenance and commissioning engineers to diagnose and test the brakes 14,16.
In order to undertake manual evacuation of the elevator car 4 when a power failure occurs, the rescue personnel on arrival at the control cabinet would firstly turn off the main power switch JH to the elevator 1 to ensure that the evacuation procedure is not interrupted even if mains power is restored. Then a manual evacuation switch JEM on the pulse electric brake opening device PEBO is turned to its on position thereby closing the circuit between the pulse generator 56 and the brake coils 34. Next a manual evacuation button DEM is pressed to connect the pulse generator 56 to the battery 52. The generator 56 will then supply a series of electrical pulses to the brake coils 34 as illustrated in the graphical representation of FIG. 4. On each such electrical pulse, the brakes are opened and the car can move under the gravitational influence of the imbalance between the mass of the car 4 and that of the counterweight 2. The manual evacuation button DEM can be repeated pressed until the elevator car 4 comes into alignment with a landing which is indicated to the rescue personnel by means of an LED on the pulse electric brake opening device PEBO. At this point, the rescue personnel can go to the landing adjacent the car level, and manually open the doors to allow any passengers to exit from the car 4.
For the purpose of comparison, a test was carried out on an installation 1 having the structure outlined above. In this first test, the elevator car 4 was sent from the uppermost floor to the lowest floor and during travel the main power switch JH was turned off to simulate a power failure. The manual evacuation procedure as outlined above was then carried out with five pulses from the pulse electric brake opening device PEBO as illustrated in FIG. 4. The duration or on-time for each pulse (i.e. from time t₀ to time t₁) was 270ms and the interval between pulses or off-time (i.e. from time t₁ to time t₂) was 1000ms.
The jerk was measured by a sensor within the car 4 as illustrated in FIG. 5 and had an average value of 7m/s². The total distance travelled by the car 4 during this test manual evacuation procedure was recorded as 280mm.
Thus assuming that in a real manual evacuation procedure the car 4 must travel 1500mm to reach the nearest landing, then it would require approximately 27 pulses (5*1500/280) and assuming that it takes 2s for each pulse, then the total time taken to evacuate the passengers would be 54s approximately (2*27).
The pulse electric brake opening device PEBO was then modified by the insertion of an adapter 60 into the interface 58 in accordance with an embodiment of the invention as shown in FIG. 6. The adapter 60 includes a circuit having two flywheel or flyback diodes 62 such that when the adapter 60 is inserted into the interface 58 both flywheel diodes 62 are connected in anti-parallel across the coil of brake 16. The purpose of the flywheel diode is to eliminate back EMF from the brake coil 34 and to continue circulation of current in the brake coil 34 when each electrical pulse from the pulse 56 generator ends.
A second test identical to the first test described above except for the inclusion of the adapter 60 was carried out. Again, the jerk was measured by a sensor within the car 4 as illustrated in FIG. 7 and had an average value of 3.5m/s². The total distance travelled by the car 4 during this test was recorded as 437mm.
Again assuming that in a real manual evacuation procedure the car 4 must travel 1500mm to reach the nearest landing, then it would require approximately 17 pulses (5*1500/437) and assuming that it takes 2s for each pulse, then the total time taken to evacuate the passengers would be 34s approximately (2*17).
Accordingly, by connecting the adapter 60 to the interface 58 of the pulse electric brake opening device PEBO, the jerk is reduced by approximately half, less pulses from the pulse electric brake opening device PEBO are required to rescue passengers from the car 4 and the total time taken to evacuate passengers to the nearest landing is reduced.
The pulse electric brake opening device PEBO was then modified by the insertion of an adapter 70 into the interface 58 in accordance with a further embodiment of the invention as shown in FIG. 8. Again, the adapter 70 includes a circuit having two flywheel or flyback diodes 62 however, on this occasion, the adapter 70 is arranged such that when it is inserted into the interface 58 a flywheel diode 62 is connected in anti-parallel across each coil of both brakes 14 and 16.
A third comparative test then was conducted. Again, the jerk was measured by a sensor within the car 4 as illustrated in FIG. 9 and had an average value of 3.5m/s². The total distance travelled by the car 4 during this test was recorded as 1547mm.
Again assuming that in a real manual evacuation procedure the car 4 must travel 1500mm to reach the nearest landing, then it would require approximately 5 pulses (5*1500/1547) and assuming that it takes 2s for each pulse, then the total time taken to evacuate the passengers would be 10s approximately (2*5).
Accordingly, by connecting the adapter 70 to the interface 58 of the pulse electric brake opening device PEBO, the jerk is reduced by approximately half in comparison to the first test, less pulses from the pulse electric brake opening device PEBO are required to rescue passengers from the car 4 and the total time taken to evacuate passengers to the nearest landing is significantly reduced.

The results of the comparative tests are summarised in Table 1 below.

Table 1

Characteristic	Test 1 (no adapter)	Test 2 (adapter 60)	Test 3 (adapter 70)
Average jerk (m/s²)	7	3.5	3.5
Pulses required for 1500mm travel	27	17	5
Total time to rescue passengers (s)	54	34	10

In conclusion, by connecting either the adapter 60 from FIG. 6 or the adapter 70 of FIG. 8 to the interface 58 of the pulse electric brake opening device PEBO, the results clearly show that not only is the jerk experienced by passengers during the manual evacuation procedure reduced considerably but also the actual time taken to evacuate the passengers is also greatly reduced.
Furthermore, since less pulses are required from the pulse electric brake opening device PEBO for the evacuation trips using the adapters 60 or 70, the lifespan of the pulse electric brake opening device PEBO itself is increased and additionally there is significantly less energy consumption from the mains-independent power supply, e.g. battery 50, which in turn will last longer.
Although the invention has been described above in relation to adapters 60;70 which are connected to the interface of existing pulse electric brake opening devices PEBO, it will be readily appreciated that flywheel diodes 62 can be incorporated internally within new pulse electric brake opening device PEBO designs as illustrated in FIG. 10 to achieve the same results. In this pulse electric brake opening device PEBO, intended to replicated that of FIG. 8, the flywheel diodes 62 are installed in anti-parallel across the outputs of the pulse generator 56 before the contacts of the manual evacuation switch JEM. As such they do not affect the characteristics of the brakes 14;16 during normal operation as they are disconnected from the brake coils 34 by contacts of the manual evacuation switch JEM.
FIG. 11 is a flowchart of a method according to the invention for evacuating elevator passengers trapped in an elevator car 4 during power disruption. Typically the method would be used in conjunction with one of the apparatuses described above with reference to FIGS. 6-10.
When, in step S1, a complete power failure or a disruption such as under-voltage occurs with the commercial mains AC power supply L1,L2,L3, the brake contactor or relay BR automatically opens and the brake 14;16 immediately engages to brake the movement of the elevator car 4. If there are passengers trapped in the elevator car 4 they can normally press an emergency button on the car operating panel which will patch them through a remote maintenance centre and a rescue personnel can be dispatched to the affected elevator installation 1.
The rescue personnel on arrival at the installation 1 would access the control cabinet and turn off the main power switch JH to the elevator 1 in step S2 to ensure that the evacuation procedure is not interrupted even if mains power is restored.
Next in step S3, at least one flywheel diode would be connected in anti-parallel with a coil 34 of an elevator brake 14;16. In the embodiments of FIG. 6 or FIG. 8, this step can be accomplished by inserting the respective adapter 60 or 70 into the interface 58 of the pulse electric brake opening device PEBO and subsequently the manual evacuation switch JEM is turned to its on position thereby closing the circuit between the pulse generator 56 and the brake coils 34. With the embodiment shown in FIG. 10, the step S3 is achieved automatically on turning the manual evacuation switch JEM to its on position.
In step S4, the manual evacuation button DEM is pressed to connect the pulse generator 56 to the battery 52. The generator 56 will then supply a series of electrical pulses to the brake coils 34. On each such electrical pulse, the brakes 14;16 are opened and the car 4 can move under the gravitational influence of the imbalance between the mass of the car 4 and that of the counterweight 2.
The manual evacuation button DEM can be repeatedly pressed, illustrated as step 5, until the elevator car 4 comes into alignment with a landing which is indicated to the rescue personnel by means of an LED on the pulse electric brake opening device PEBO. At this point, in step S6, the rescue personnel can go to the landing adjacent the car level and manually open the doors to allow any passengers to exit from the car 4.
In step S7, the elevator 1 can be prepared for normal operation once again when the mains power is restored by reversing the procedures carried out in steps S2 and S3. After which the method for manually evacuating passengers is terminated in step S8.

Claims

An adapter (60;70) configured to be inserted across at least one output of a pulse electric brake opening device (PEBO) used during power disruption to open at least one elevator brake (14;16), the adapter comprising at least one flywheel diode (62) configured for anti-parallel arrangement with an output of the pulse electric brake opening device.
An adapter (70) according to claim 1 wherein at least one flywheel diode (62) is configured in anti-parallel with all outputs of the pulse electric brake opening device.
An adapter according to claim 1 or claim 2 configured to be inserted into an interface (58) of the pulse electric brake opening device.
An arrangement of an adapter according to any preceding claim and a pulse electric brake opening device (PEBO) configured to accept the adapter.
An arrangement according to claim 4 wherein the pulse electric brake opening device includes a mains-independent power supply (52) and a pulse generator (56).
An arrangement according to claim 5 further comprising a manual evacuation switch (JEM) configured to selectively connect the pulse generator to one or more brake coils (34).
An arrangement according to claim 5 or claim 6 further comprising a manual evacuation button (DEM) configured to selectively connect the pulse generator to the mains-independent power supply.
A pulse electric brake opening device (PEBO) configured to open at least one elevator brake (14; 16) during power disruption comprising a pulse generator (56) and at least one flywheel diode (62) arranged in anti-parallel with an output of the pulse generator.
A pulse electric brake opening device according to claim 8 wherein at least one flywheel diode (62) is arranged in anti-parallel with each output of the pulse generator.
A pulse electric brake opening device according to claim 8 or claim 9 further comprising a manual evacuation switch (JEM) configured to selectively connect the pulse generator to one or more brake coils (34).
A pulse electric brake opening device according any one of claims 8 to 10 further comprising a manual evacuation button (DEM) configured to selectively connect the pulse generator to a mains-independent power supply (52).
A method for evacuating elevator passengers during power disruption comprising the steps of:
providing at least one flywheel diode in anti-parallel with a coil of an elevator brake (S3); and

providing one or more electrical pulses to the coil (S4).
A method according to claim 12 further comprising the step of disconnecting the elevator from a commercial mains AC power supply (S2).
A method according to claim 12 or claim 13 further comprising the step of manually opening elevator doors when the elevator car comes into alignment with a landing (S5).