EP0903314B1 - Device for monitoring the drive control of elevators - Google Patents

Description

The invention relates to a monitoring device for a drive control for elevators.

In today's elevator systems with frequency converter drives and microprocessor controls become Supervision of the safety circuit and with it related follow-up actions, such as braking, Switch motor current on and off and charge the DC link of the frequency converter with one defined inrush current, mainly electromechanical contactors used.

When using electromechanical contactors or also Relays wear out the mechanical contacts. Further cause contactors or relays during switching operations considerable noise emissions, which are particularly associated with Elevator systems in residential and commercial buildings as disturbing prove. Ultimately, contactors and relays, too due to their limited lifespan and frequent Substitution, considerable financial expenses.

• Bei einer Aufzugsinstallation kommen sehr lange, parallele verlegte elektrische Leitungen vor. Durch die Kapazität zwischen den Leitern kann Wechselspannung von einem Leiter auf den andern übertragen werden. Durch diesen Effekt kann die Netzspannung in den Sicherheitskreis eingekoppelt werden. Dies kann zur Folge haben, dass Schütze oder Relais nicht abfallen, wenn ein Sicherheitskontakt im Sicherheitskreis öffnet, weil bei Wechselstrom-Schützen oder -Relais die Abfallspannung etwa zehnmal kleiner als die Anzugsspannung ist.
• Das selbe kann passieren, wenn die Spannung des Sicherheitskreises von einem Leiter des Sicherheitskreises zu einem Sicherheitskontakt auf den zurückführenden Leiter übertragen wird.
• Wechselstrom-Schütze oder -Relais benötigen einen grossen Einschaltstrom. Bei einem langen Sicherheitskreis wird der Innenwiderstand so gross, dass für das zuverlässige Einschalten spezielle Massnahmen zur Spannungsanpassung erforderlich sind.
• Die Betriebsspannung des Sicherheitskreises ist meistens im Bereich von 110 bis 230 Volt. Deswegen ist an allen zugänglichen Stellen ein Berührungsschutz erforderlich.
• Die Lebensdauer der Schütze und Relais ist aufgrund des mechanischen Verschleisses stark beschränkt.

Disadvantages also result from the operating mode of the safety circuit. To date, the checking or the detection of the state of the safety circuit has been carried out using electromechanical contactors or relays. These contactors or relays serve as sensors. In an AC safety circuit, however, this has various disadvantages:

• In an elevator installation there are very long, parallel electrical lines. Due to the capacitance between the conductors, AC voltage can be transferred from one conductor to the other. This effect enables the mains voltage to be coupled into the safety circuit. As a result, contactors or relays do not drop out when a safety contact in the safety circuit opens because the drop-out voltage in AC contactors or relays is about ten times less than the pull-in voltage.
• The same can happen if the voltage of the safety circuit is transmitted from a conductor of the safety circuit to a safety contact on the returning conductor.
• AC contactors or relays require a large inrush current. With a long safety circuit, the internal resistance becomes so great that special measures for voltage adjustment are required for reliable switching on.
• The operating voltage of the safety circuit is usually in the range from 110 to 230 volts. This is why touch protection is required at all accessible locations.
• The service life of the contactors and relays is severely limited due to the mechanical wear.

• Der Gleichstrom führt zu Abnützungen an den Kontaktübergängen der Sicherheitskontakte durch Materialwanderung.

There are also disadvantages with a DC safety circuit:

• The direct current leads to wear on the contact transitions of the safety contacts due to material migration.

EP 0 535 205 describes a monitoring device for a control device for elevator and conveyor systems become known, which with contactless triggerable, electronic, testable, comprehensive sensor Switching device is provided, with the help of State of the sensor is detectable. These non-contact Switching devices should, for example, for the Monitoring the door latches can be used.

With the monitoring device described above Switching devices used, although the disadvantages of Eliminate electromechanical switches, but by one Are many times more expensive, so that a stake out Not worth the cost. Furthermore, this requires Monitoring device a considerable Circuitry. Because of the capacitive crosstalk can with long electrical lines, like this at a safety circuit is the case with elevator systems, no circle can be formed. At the end of a line that can run across multiple contacts Signal converter are used so that the parallel to Source signal returning signal from any differentiated capacitively coupled source signal can be.

The invention has for its object a Monitoring device for a drive control for To propose lifts of the type mentioned at the outset does not have the aforementioned disadvantages.

This object is achieved by the in claim 1 characterized invention solved.

The advantages achieved by the invention are in essential to see that the Monitoring device from a safety circuit sensor system and there is a motor and brake circuit, that are related, the Monitoring device only electronic components, bypassing galvanic Separation points. By using it electronic components can be based on electromechanical Switching elements that have galvanic separation points, to be dispensed with. By using exclusively electronic components becomes a significant reduction of the noise level is reached because there are no switching noises arise more. This particularly affects machine room-less elevator systems advantageous. Further can be achieved by using conventional electronic Components massively reduce the manufacturing costs and high security and reliability of the Monitoring device can be guaranteed.

Fig.1

eine schematische Darstellung einer Überwachungseinrichtung für einen Wechselstrom-Sicherheitskreis mit einer Sicherheitskreis-Sensorik und einem Motor- und Bremsschaltkreis,

Fig.2

eine schematische Darstellung einer Überwachungseinrichtung für einen Gleichstrom-Sicherheitskreis mit einer Sicherheitskreis-Sensorik und einem Motor- und Bremsschaltkreis,

Fig.3

eine schematische Darstellung eines Motor- und Bremsschaltkreises,

Fig.4

eine erste Variante einer Motorsteuerung,

Fig.5

Überwachungsfunktionen einer Motorsteuerung gemäss der ersten Variante,

Fig.6

eine zweite Variante einer Motorsteuerung,

Fig.7

Überwachungsfunktionen einer Motorsteuerung gemäss der zweiten Variante,

Fig.8

eine schematische Darstellung einer Bremssteuerung, und

Fig.9

eine schematische Darstellung des Aufbaus eines intelligenten Schutz-Systems.

In the drawing, an embodiment of the invention is shown and explained in more detail below.
Show it:

Fig.1

1 shows a schematic representation of a monitoring device for an AC safety circuit with a safety circuit sensor system and a motor and brake circuit,

Fig.2

1 shows a schematic representation of a monitoring device for a direct current safety circuit with a safety circuit sensor system and a motor and brake circuit,

Figure 3

a schematic representation of a motor and brake circuit,

Figure 4

a first variant of a motor control,

Figure 5

Monitoring functions of a motor control according to the first variant,

Figure 6

a second variant of an engine control,

Figure 7

Monitoring functions of an engine control according to the second variant,

Figure 8

a schematic representation of a brake control, and

Figure 9

a schematic representation of the structure of an intelligent protection system.

In Fig.1 is a schematic representation of a Monitoring device 1 with a safety circuit sensor system 2 and a motor and brake circuit 3 for an AC safety circuit 4 shown. The Safety circuit sensor 2 is for monitoring the Safety circuit 4, for example whether the Safety circuit 4 is open or closed. The motor and brake circuit 3 for it resulting follow-up actions in relation to a Drive motor 5 respectively. an associated brake 6. Im Safety circuit 4, the elevator car and shaft is looped, there are several contacts 7, for example on the landing doors, which are checked have to.

The following is a solution for an AC safety circuit 4 and a safety circuit sensor system 2 described with exemplary values:

A signal source 10 of the safety circuit 4 must be in the Frequency from the mains voltage (230V, 50 / 60Hz) distinguishable, for example 200Hz, and the voltage should be 24V (protection against contact).

Due to the structure of the safety circuit sensors 2 be sure that at any Combination of three errors under any Operating conditions the following device is switched off can be. Therefore, the safety circuit sensor system 2 deliver four output signals. Security against three Errors require the use of four sensors included Evaluation electronics. Because of the contact crosstalk capacity is between the heads of the safety circuit 4 Voltage measurement alone cannot determine whether the load / measuring resistor has an interruption. Therefore, the Voltage and current of the safety circuit 4 measured become. The current measurement must go through an element with energy transfer.

The distinction between the operating frequency of 200Hz and the interference frequency of 50 / 60Hz as well as the Phase shift in the case of capacitive Contact crosstalk takes place through synchronization with the Signal source 10. The maximum possible current in the open Safety circuit 4 should be at least three times smaller than the minimum current in the closed safety circuit 4, in which a current sensor switches on. Desweitern should turn off a voltage sensor when the Phase shift from the source signal more than is sixty degrees.

Optocouplers, for example, are used as current sensors 15 (or also transformers) with a defined Transfer factor used. So that a defined Current threshold can be determined is a Output transistor 16 fed with a current source. This will make for a negative and a positive Safety circuit current each generates a signal that subsequently filtered and in an evaluation unit 17 is processed digitally. These two signals are in the evaluation unit 17 with a Synchronization signal from a synchronization unit 18 linked. This can cause false signals, for example, the interference frequency 50 / 60Hz, at least are suppressed every half-period. Further includes the evaluation unit 17 of the current sensor 15 flip-flops, which generate a reset pulse for a counter if there is no valid signal in a half period would. In the absence of a synchronization signal, the However, flip-flops do not generate reset pulses. Out for this reason, a monitoring circuit sets the counter back if the synchronization signal is missing.

The output signals are combined and put on one Led counter. With a defined meter reading a current sensor output 20 reaches a state 1, which means that safety circuit 4 is closed. At the same time, the counter input is blocked.

The digital part of the evaluation unit 17 can also be used PAL, GAL, EPLD or ASIC can be realized.

In the synchronization unit 18 Synchronization of the current sensors 15 and Voltage sensors 25 from the source signal Square wave generated. An operational amplifier is wired as a bandpass and ensures at the same time a level adjustment. Low and high signals Frequencies are suppressed.

The voltage sensor 25 contains an operational amplifier which is wired the same way as in the Synchronization unit 18 and one Operational amplifier that inverts this signal. Analog switches transmit the signals from these two Operational amplifier piece by piece to an active, unbalanced filter (connected as active low pass Operational amplifier). The sensor input signal is correct coincide with the source signal, the Analog switch like a rectifier. If not Case, the sensor input signal is dismembered and by subsequent filter greatly weakened. A diode in front The low pass ensures that negative input signals amplified (approx. ten times) on a filter capacitor in Act in the direction of switching off. Another Operational amplifier is included as a threshold switch Hysteresis switches and supplies the signal on Voltage sensor output 26.

The four output signals of the safety circuit sensors 2 the sensors described above and synchronization carried out twice.

Taps in safety circuit 4 for diagnostic functions do not have to be fail-safe and are built like a voltage sensor 25, since the safety circuit 4 through the taps are not heavily loaded in terms of current may.

As a variant of the solution described above, the Signal evaluation also implemented with digital sampling become. In the following the circuit is based on the Voltage sensor described. The source signal becomes generates a scanning signal via synchronization, which for Time of the voltage maximum has the state 1. Lies at this time the voltage of the safety circuit 4 above a threshold, a count for one Counter generated. If this is not the case or does it fall If the scanning signal is off, the counter receives a reset pulse.

In Figure 2 is a schematic representation of a Monitoring device 30 for a direct current safety circuit 31 with a safety circuit sensor system 32 and a motor and brake circuit 33. Die Safety circuit sensor system 32 is for monitoring the Safety circuit 31 responsible, the engine and Brake circuit 33 for the resulting Follow-up actions with respect to a drive motor 34 respectively. an associated brake 35. In the safety circuit 31, the is looped through the elevator car and shaft several contacts 36, for example on the shaft doors, available that need to be checked.

The safety circuit sensor system 32 is equipped with a DC-operated safety circuit 31 much easier than with alternating current, as already taken from Fig.2 can be. The synchronization with the source signal omitted and the evaluation only has to be carried out for one current / voltage direction will be realized.

The following is a solution for a DC safety circuit 31 and a safety circuit sensor system 32 described with exemplary values:

A signal source 40 of the safety circuit 31 is connected DC operated. Voltage and current in the Safety circuit 31 must be selected so that the Contacts 36 the material migration is negligibly small is. The voltage should continue for reasons of Protection against contact be less than 60V. From these For example, the voltage can be set to 48V (Protection against contact). The coupling of the Mains voltage in the safety circuit 31 forms the Operation with direct current continues to be a source of interference. The Filtering out this disturbance leads to the Response time of the evaluation circuit longer than the previous one AC safety circuit described.

A current sensor 45 consists of an optocoupler Power supply as in the AC safety circuit above is described. It will be a signal generated, which is then in an evaluation unit 46 is filtered by 50 Hz interference signals to the mains voltage suppress and digitally processed. in the The structure of the evaluation unit 46 is essential identical to that of the AC safety circuit.

For example, a voltage threshold switch is used as the voltage sensor 47 with hysteresis and a subsequent one Filters used to supply 50Hz noise to the mains voltage suppress.

The four output signals of the safety circuit sensors 32 are also available when operating with direct current the sensors described above are carried out twice.

Safety circuit taps for diagnostic functions are also here how to build the voltage sensors 47.

3 shows a representation of the monitoring device 1, 30 with the motor and brake circuit 3, 33. The one in FIGS. 1 and 2 is also shown schematically described safety circuit 4, 31 with the signal source 10, 40, and the safety circuit sensors 2, 32 with the Connection to the motor and brake circuit 3, 33, respectively. with the current sensor outputs 20 and the voltage sensor outputs 26th

Mainly there is the motor and brake circuit 3, 33 from a frequency converter power unit 50, a VVVF drive / control part 51 (where VVVF variable Voltage and variable frequency means) one intelligent protection system 52 and a brake control 53rd

The frequency converter power section 50 contains all of them Power electronics elements around the mains voltage in one DC link DC voltage and from it into three-phase current convert for the drive motor 5, 34. The VWF drive / control part 51 is the summary of the Components of drive control and elevator control. The VVVF drive / control part 51 controls the Frequency converter power section 50 and on the other hand from the intelligent protection system 52 as an interface addressed. The intelligent protection system 52 is that Safety module of the electric drive. It exists from an electronic safety circuit and monitors all safety-related functions. If the Safety circuit 4, 31 opens, activates the intelligent one Protection system 52 the brake 6, 35 and switches the Energy flow to the drive motor 5, 34 from. Put that intelligent protection system 52 found a malfunction the elevator is also stopped. The Brake control 53 contains all the switching elements to the Switch brake 6, 35 on and off safely. The Brake control 53 must be the highest Security requirements meet and is therefore direct and continuously from the intelligent protection system 52 checked.

4 shows a first variant of a motor control. The interface between the VVVF drive / control part 51 and the intelligent protection system 52 is hereby very simple without electromechanical contactors. The three-phase energy flow to the drive motor 5, 34 can be blocked and released by the intelligent protection system 52 by means of two switching elements, an input rectifier 55 and an IGBT inverter 56, via a VVVF drive / control part 51. The input rectifier 55, which is fed by three phases L1, L2, L3, consists of half a thyristor bridge with rectifier control 57. The input rectifier 55 can be switched on and off by the rectifier control 57. When it is switched off, a small current flows through a charging resistor R _c . Control signals T1 to T6 of a pulse width modulation PWM for controlling the IGBTs of the inverter 56 are checked and released as a block by the intelligent protection system 52 via a logic link in the VVVF drive / control part 51.

Measurement signals of the motor current i _U , i _V , I _w are preprocessed by the VVVF drive / control part 51 and passed on to the intelligent protection system 52.

The description of the monitoring function of the intelligent protection system 52 for the release and that Blocking is shown in Figure 5 based on the time The procedure for switching the signals is described and corresponds to the first variant of the engine control according to Fig. 4.

Description of the sequences: Begin:

The VVVF drive / control part 51 switches s1 = 1 and thus informs the intelligent protection system 52 that a journey is to be started. Once the Safety circuit is closed, gives the intelligent Protection system 52 by s2 = s5 = 1 free converter operation. The intelligent protection system 52 measures the time t1 the start approval, which is only valid for a certain time is. The VVVF drive / control part 51 gives s4 = 1 the IGBT's free to the holding torque in the drive motor 5, 34 to build. The motor current iU, iV, iW begins rise and i = 0 becomes zero. The intelligent protection system 52 releases the brake 6, 35 with s8 = 1. When the VVVF drive / control part 51 has built up the holding torque, the brake 6, 35 with s7 = 1 via a brake control 53 activated. If the brake shoes are removed, KB = 1 and the journey can begin.

Journey:

The intelligent protection system 52 measures the time t2 switching off the brake magnet current. Exceed this Time a certain value, becomes an emergency stop initiated. This monitoring is imperative so it is ensured that all elements within one be checked once at a certain time.

Stop:

The cabin stands still and the VVVF drive / control section 51 switches the brake via s7 = 0 6, 35 from. After KB = 0, the VVVF drive / control section controls 51 the motor current towards zero (i = 0) = 1 and then switches the IGBT module 56 as well s4 = 0 and the rectifier 55 with s1 = 0. The Shutdown sequence is provided by the intelligent protection system 52 supervised. The stop sequence ends with s5 = s2 = 0. The Time t3 of the shutdown sequence is the intelligent Protection system 52 monitors.

Intermediate circuit voltage test:

Following the stop sequence is a DC link capacitor C through TB and RB from the VVVF drive / control section 51 controlled, so far unloaded, that the intelligent protection system 52 based on a DC link voltage uZK can determine whether the Input rectifier 55 is turned off. After that is the drive for a certain time (in the range of Minutes or hours) for a new start. If this time is exceeded, a new one DC link voltage test can be performed.

Emergency stop:

An emergency stop is initiated when the intelligent Protection system 52 detects a malfunction or the Safety circuit is interrupted. The protection system 52 switches brakes 6, 35 off via s8 = 0. With s8 = 0 this becomes VVVF drive / control part 51 communicated that a There is an emergency stop, the motor current is regulated to zero and the IGBT module and the rectifier are switched off got to. The shutdown sequence is provided by the intelligent protection system 52 monitors. It is checked that the time t3 a certain value during the switch-off process exceeds. If the permissible time is exceeded emergency shutdown via s5 and s2. With s5 = s2 = 0 the emergency stop sequence ends.

6 shows a second variant of a motor control. Instead of the input rectifier 55, a Comprehensive circuit for regenerative power supply be used. Because of this, in this second variant a solution without monitoring the Input rectifier 55 described. The will continue IGBT's of the inverter 56 from the intelligent protection system 52 no longer as a block but in groups of two tested and approved.

The description of the monitoring function of the intelligent protection system 52 for the release and that Blocking is shown in Figure 7 based on the time The procedure for switching the signals is described and corresponds to the second variant of the Motor control according to Fig. 6.

Description of the sequences: standstill:

The switching means (IGBT) and the brake 6, 35 are through the intelligent protection system 52 locked. s2, s4, s6 and s8 are zero.

Start Preparation:

The VVVF drive / control part 51 wants to drive kick off. Before the journey from the protection system 52 is released, the switching means must be checked. For this purpose, the VVVF drive / control part 51 generates the PWM signal for the transistors so they're for the test's can be switched on. The transistors can are not switched on statically for a long time, because the current in the motor winding is at a standstill would be big. By switching on s1 the VVVF drive / control part divides 51 the protection system 52 with that T1 and T6 should be checked. The protection system 52 turns on s2. The currents iU and iW increase. The Protection system 52 measures the current and switches after one defined time s2 again, so that the current against Zero goes. Then the same thing happens with the other two pairs of transistors. After a successful test and if the safety circuit is closed, there is intelligent protection system 52 through the converter 56 s2 = s4 = s6 = 1 free to travel. The release is only for one certain time is valid, the time t1 from the Start clearance is measured.

Begin:

The VVVF drive / control part 51 controls the Transistors to the holding torque in the drive motor 5, 34 to build. The intelligent protection system 52 gives that Brake 6, 35 with s8 = 1 free. When the VVVF drive / control part 51 has built up the holding torque, the brake 6, 35 with s7 = 1 via the brake controller 53 activated. If the brake shoes are removed, KB = 1 and the journey can begin.

Journey:

The intelligent protection system 52 measures the time t2 brake activation. If t2 exceeds a certain one Value, an emergency stop is initiated. This surveillance is imperative to ensure that everyone Elements checked once within a certain time become.

Stop:

The cabin stands still and the VVVF drive / control section 51 switches the brake via s7 = 0 6, 35 from. After KB = 0, the VVVF drive / control section regulates 51 the motor current towards zero and then switches off s1, s3 and s5. Then switches the protection system 52 also s2, s4 and s6. the time t3 the shutdown sequence is monitored by the protection system 52.

Emergency stop:

An emergency stop is initiated when the protection system 52 detects a malfunction or the safety circuit is interrupted. The protection system 52 switches via s8 = 0 the brake 6, 35 off. With s8 = 0 the VVVF drive / control part 51 informed that an emergency stop is present, the motor current is regulated to zero and must be switched off. The intelligent protection system 52 monitors that the time t3 has a certain value not exceed, otherwise using s2, s4 and s6 off.

Fig. 8 shows an embodiment of the brake control 53. The brake control 53 is responsible for the control the brake 6, 35. It must absolutely be prevented can that the braking current is no longer turned off can be. The elevator car could drift away, causing too can lead to a dangerous state. For this reason the brake voltage should be reduced as soon as the The armature of the MGB brake magnet is attracted. Before the Protection system 52 turns on the braking current through voltage measurement for all switching elements the switched off state is determined.

The DC voltage for operating the brake 6, 34 can either with a rectifier GR, a transformer or with a switching power supply are generated. It has Switching power supply the advantage that the output voltage is on, off and switchable and a small tolerance having.

The energy of the brake magnet MGB can be converted into heat when switched off, for example in a varistor R3, or fed back into a smoothing capacitor C _G. The power can be reduced in this circuit by clocking a transistor. For example, if a transistor T _T1 , T _{T2 is} only switched on 50%, the brake magnet current flows through a free-wheeling diode D1, D2 during the pause. This halves the average braking voltage.

When the brake 6, 34 is switched on, the transistors T _T1 , T _T2 can be functionally _tested by alternately briefly switching off the transistors. While the transistor is switched off, the current flows through the freewheeling diode D1, D2 in the same branch. When the brake 6, 34 is switched off, a small current flows through the resistors R1, R2. With the aid of the voltages u1, u2, u3 it can thus be checked by the protection system 52 whether the transistors T _T1 , T _{T2 are} short-circuited. The power in the brake 6, 34 can be controlled as desired by increasing the switch-off time.

As a further variant, in order to increase security Series for the MGB brake magnet at point X1 Relay contact can be switched. This relay is from intelligent protection system 52 controlled so that it is in Normal operation switches off. Only if one If the transistor is defective, the relay needs the braking current can switch off. The function check of this relay over the protection system 52 can by voltage measurement or by means of a positively driven break contact respectively.

Fig. 9 shows a schematic representation of the intelligent protection system 52 with the associated Interfaces to safety circuit sensors 2, 32 for VVVF drive / control part 51, for brake control 53 and to a variant like the one described above necessary brake relay control 60. The in the functions described in the preceding figures and Processes of the intelligent protection system 52 are shown in Form of a program of microcontrollers 61, 62 two-channel controlled and monitored or processed. In a state comparator 63 is used to obtain specific data from the two microcontrollers 61, 62 compared with each other. The program detects errors in the switching process the safety circuit sensors 2, 32, the VVVF drive / control section 51, the frequency converter power section 50, the brake control 53 and the intelligent protection system 52 and prevents dangerous states of the elevator by locking the Motor current and by switching off the braking current.

Claims (7)

1. Monitoring equipment (1, 30) for a drive control for lifts, wherein the monitoring equipment (1, 30) monitors a safety circuit (4, 30), which is provided with contacts (7, 30), is operated by direct or alternating current from a signal source (10, 40) and initiates the sequential actions resulting therefrom, such as the actuation of a brake (6, 35) or the switching-on or switching-off of the current of a motor (5, 34), wherein the monitoring equipment (1, 30) consists of a safety-circuit sensor system (2, 32) and a motor switching and/or brake switching circuit (3, 33), which stand in connection one with the other, characterised in that the monitoring equipment (1, 30) consists exclusively of electronic components.
2. Monitoring equipment (1, 30) according to claim 1, characterised in that the safety-circuit sensor system (2, 32) in the case of the operation of the safety circuit (4) by direct current consists of at least a respective current sensor (15) with evaluating unit (17) and a voltage sensor (25).
3. Monitoring equipment (1, 30) according to claim 1, characterised in that the safety-circuit sensor system (2, 32) in the case of the operation of the safety circuit (4) by alternating current consists of at least a respective current sensor (15) with evaluating unit (17), a synchronising unit (18) and a voltage sensor (25).
4. Monitoring equipment (1, 30) according to one of claims 1 to 3, characterised in that the motor switching and/or brake switching circuit (3, 33) consists substantially of a frequency converter power unit (50), a drive/control part (51) of variable voltage and variable frequency, an intelligent protection system (52) and a brake control (53), wherein the intelligent protection system (52) discerns all monitoring and controlling functions, which are relevant to safety, of the safety-circuit sensor system (2, 32), of the drive/control part (51) of variable voltage and variable frequency, of the frequency converter power unit (50) and of the brake control (53).
5. Monitoring equipment (1, 30) according to one of claims 1 to 4, characterised in that the intelligent protection system (52) executes the monitoring and controlling functions, which are relevant to safety, in two channels and comprises a state comparator (63) for the comparison of the two channels.
6. Monitoring equipment (1, 30) according to one of claims 1 to 5, characterised in that a microcontroller (61, 62) with program is provided for each channel.
7. Monitoring equipment (1, 30) according to one of claims 1 to 6, characterised in that a program is provided, which recognises faults in the operating sequence of the switching operations of the safety-circuit sensor system (2, 32), of the drive/control part (51) of variable voltage and variable frequency, of the frequency converter power unit (50), of the brake control (53) and of the intelligent protection system (52) and prevents dangerous states of the lift.

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