Condition monitoring of an inductive braking device

1. A method for condition monitoring of an inductive braking device of an elevator car in an elevator shaft, the method comprising:

causing electromechanical brakes to hold the elevator car stationary in the elevator shaft; then

causing actuation of a braking condition for the elevator car with the inductive braking device; then

causing the electromechanical brakes to lift while the inductive braking device is in the braking condition; then

determining a value associated with the inductive braking device in response to causing the electromechanical brakes to lift while the inductive braking device is actuated; and then;

determining an operating condition of the inductive braking device based on the value.

2. The method of claim 1 , wherein determining the value comprises determining a speed of the elevator car, and

wherein determining the operating condition of the inductive braking device further comprises:

comparing the speed to a predefined speed threshold; and

determining that the inductive braking device is operational when the speed does not exceed the predefined speed threshold.

3. The method of claim 2 , further comprising:

determining a location of the elevator car in the elevator shaft; and

applying a predefined speed threshold that is specific for the location of the elevator car in the elevator shaft.

4. The method of claim 1 , wherein determining the value comprises:

determining a torque ripple based on at least one of signals from an accelerometer determining vibrations from the elevator car, signals from a motor encoder determining vibrations from a hoisting machine, signals from an encoder determining vibrations from an overspeed governor, or signals from a car encoder determining vibrations from the elevator car, and

wherein determining the operating condition of the inductive braking device further comprises:

comparing the determined torque ripple to a reference torque ripple; and

determining that the inductive braking device is not operational when the torque ripple has substantially increased compared to the reference torque ripple.

5. The method of claim 1 , wherein determining the value comprises:

determining a three-phase current of a motor of a hoisting machine of the elevator from current sensors of a frequency converter coupled to the motor, and

wherein determining the operating condition of the inductive braking device further comprises:

determining that the inductive braking device is not operational when at least one of the current sensors indicates that a phase is missing current.

6. The method of claim 1 , wherein determining the value comprises:

determining voltage from poles of a motor of a hoisting machine of the elevator, and

wherein determining the operating condition of the inductive braking device further comprises:

determining that the inductive braking device is not operational when at least one pole shows voltage.

7. The method of claim 1 , further comprising:

repeating the condition monitoring when the operation condition indicates that the inductive braking device is not operational.

8. The method of claim 1 , further comprising:

repeating the condition monitoring of the inductive braking device at regular intervals.

9. The method according to claim 1 , further comprising:

in response to determining the operating condition of the inductive braking device, taking the elevator car out of service when the inductive braking device is not operational.

10. The method of claim 1 , further comprising:

in response to determining the operating condition of the inductive braking device, enabling the use of the inductive braking device as an independent braking function or as an assistive brake when the inductive braking device is operational.

11. A computer program embodied on a non-transitory computer readable medium and comprising program code, which when executed by at least one processing unit, causes the at least one processing unit to perform the method of claim 1 .

12. An apparatus for condition monitoring of an inductive braking device of an elevator car in an elevator shaft, the apparatus comprising:

means for causing electromechanical brakes to hold the elevator car stationary in the elevator shaft;

means for causing actuation of a braking condition for the elevator car with the inductive braking device while the electromechanical brakes hold the elevator car stationary in the elevator shaft;

means for causing the electromechanical brakes to lift while the inductive braking device is in the operative condition after causing the actuation of the braking condition for the elevator car with the inductive braking device;

means for determining a value associated with the inductive braking device in response to causing the electromechanical brakes to lift while the inductive braking device is actuated; and

means for determining an operating condition of the inductive braking device based on the value.

13. The apparatus of claim 12 , wherein the means for determining the value comprises means for determining a speed of the elevator car, and

wherein the means for determining the operating condition of the inductive braking device further comprises:

means for comparing the speed to a predefined speed threshold; and

means for determining that the inductive braking device is operational when the speed does not exceed the predefined speed threshold.

14. The apparatus of claim 13 , further comprising:

means for determining a location of the elevator car in the elevator shaft; and

means for applying a predefined speed threshold that is specific for the location of the elevator car in the elevator shaft.

15. The apparatus of claim 12 , wherein the means for determining the value comprises determining a three-phase current of a motor of a hoisting machine of the elevator from current sensors of a frequency converter coupled to the motor, and

wherein means for determining the operating condition of the inductive braking device further comprises:

means for determining that the inductive braking device is not operational when at least one of the current sensors indicates that a phase is missing current.

16. The apparatus of claim 12 , wherein the means for determining the value comprises means for determining voltage from poles of a motor of a hoisting machine of the elevator, and

wherein the means for determining the operating condition of the inductive braking device further comprises:

means for determining that the inductive braking device is not operational when at least one pole shows voltage.

17. The apparatus of claim 12 , further comprising:

means for repeating the condition monitoring when the operation condition indicates that the inductive braking device is not operational.

18. The apparatus of claim 12 , further comprising:

means for repeating the condition monitoring of the inductive braking device at regular intervals.

19. The apparatus of claim 12 , further comprising:

means for, in response to determining the operating condition of inductive braking device, taking the elevator car out of service when the inductive braking device is not in operating condition.

20. The apparatus of claim 12 , further comprising:

means for, in response to determining the operating condition of inductive braking device, enabling the use of inductive braking device as independent braking function or as an assistive brake when the inductive braking device is in operating condition.

21. An elevator system comprising:

at least one elevator car; and

the apparatus of claim 12 .

22. An apparatus for condition monitoring of an inductive braking device of an elevator car in an elevator shaft, the apparatus comprising:

means for causing electromechanical brakes to hold the elevator car stationary in the elevator shaft;

means for causing actuation of a braking condition for the elevator car with the inductive braking device;

means for causing the electromechanical brakes to lift while the inductive braking device is in the operative condition;

means for determining a value associated with the inductive braking device in response to causing the electromechanical brakes to lift while the inductive braking device is actuated; and

means for determining an operating condition of the inductive braking device based on the value,

wherein the means for determining the value comprises means for determining a torque ripple based on at least one of signals from an accelerometer determining vibrations from the elevator car, signals from a motor encoder determining vibrations from a hoisting machine, signals from an encoder determining vibrations from an overspeed governor, or signals from a car encoder determining vibrations from the elevator car, and

wherein the means for determining the operating condition of the inductive braking device further comprises:

means for comparing the determined torque ripple to a reference torque ripple; and

means for determining that the inductive braking device is not operational when the torque ripple has substantially increased compared to the reference torque ripple.