System to Control, Protect and Monitor the Status of Forced Cooling Motors for Power Transformers and Similar

• US 20080266728A1
• Filed: 08/17/2006
• Published: 10/30/2008
• Est. Priority Date: 10/03/2005
• Status: Active Grant

• Current Assignee: Eduardo Pedrosa Santos
• Original Assignee: Eduardo Pedrosa Santos
• Inventors: Santos, Eduardo Pedrosa
• Granted Patent: US 8,054,609 B2
• Time in Patent Office: Days
• US Class Current: 361/24
• CPC Class Codes: H02H 3/006 Calibration or setting of parameters
• CPC Class Codes: H02H 7/0822 Integrated protection, motor control centres

Abstract

System to control, protect and monitor the status of forced cooling motors for power transformers and similar, is preferably applied to power transformers and auto-transformers, and this system turns conventional (1) cooling motors into “intelligent” motors, operating in a totally autonomous manner, whose electronic module (2) is installed on the actual motor cover, more specifically on the connection box (3) and is interconnected by a communication network to a digital system (4) without the need to use any external control, protection and monitoring elements or exaggerated panels for functioning thereof.

Claims

1. A system to control, protect and monitor the status of forced cooling motors for power transformers and similar, wherein conventional (1) cooling motors are turned into “

intelligent”

motors, operating in a totally autonomous manner, whose electronic module (2) is installed on the actual motor cover, more specifically on the connection box (3) and interconnected by a- communication network to a digital system (4) without the need to use any external control, protection and monitoring elements or exaggerated panels for functioning.

2. A system to control, protect and monitor the status of forced cooling motors for power transformers and similar, in accordance with claim 1, wherein an electronic module (2) is installed directly in the connection box (3), containing a voltage and current measurement module (M) in a CPU micro-controlled that also interacts with an interface composed of a keyboard and display (TD);

connect-disconnect control (5) fed by any type of voltage and current (TC);

serial communication (9) interconnected to a digital communication network system (4) able to connect and disconnect (5), acquire alarms (8) make measurements (9) in the motor (1) for maintenance purposes;

the CPU through output contacts (S) is able to make self-diagnosis signals (10), alarms (8) and status (6) motor connected/disconnected preserving it against damages due to mechanical or electrical overloading, with self-diagnosis signals (11), alarms (8) and the status (6) of the connected/disconnected motor.

3. A system to control, protect and monitor the status of forced cooling motors for power transformers and similar, in accordance with claim 1, wherein the system measures (M) the current consumed by the motor (1) through the electronic circuits located in the module (2) that digitalizes this information.

4. A system to control, protect and monitor the status of forced cooling motors for power transformers and similar, in accordance with claim 3, wherein the thermal protection (not shown) is performed digitally by specific software located in the CPU contained in the module (2).

5. A system to control, protect and monitor the status of forced cooling motors for power transformers and similar, in accordance with claim 4, wherein the software performs the adjustment of the motor'"'"'s (1) nominal current for thermal protection (not shown) in a wide range of values, allowing that same module (2) to be applied in motors (1) with different nominal currents.

6. A system to control, protect and monitor the status of forced cooling motors for power transformers and similar, in accordance with claim 4, wherein the proposed system has an automatic thermal protection adjustment function in the motors that eliminates the need for manual adjustments.

7. A system to control, protect and monitor the status of forced cooling motors for power transformers and similar, in accordance with claim 6, wherein an automatic thermal protection adjustment function comprises a learning stage in which the control (5) and protection system will connect the motor (1) and make the measurements (M) of the current consumed by the motor (1) during the predetermined learning time, which may be altered by the user.

8. A system to control, protect and monitor the status of forced cooling motors for power transformers and similar, in accordance with claim 7, wherein an automatic thermal protection activation current adjustment is determined by adding together the margin of tolerance that is also predetermined, in a percentage of the current measured over the maximum value of the current measured during the period, and the margin of tolerance may be altered by the user.

9. A system to control, protect and monitor the status of forced cooling motors for power transformers and similar, in accordance with claim 8, wherein a system measures (M) the voltage in each motor input phase and carries out in its firmware the protection functions against underloading, overloading, phase failure, voltage imbalance between phases and phase inversions, disconnecting the motor (1) in the event of the occurrence of any of these conditions and signaling (10) the occurrence in order for the operator to take all necessary measures.

10. A system to control, protect and monitor the status of forced cooling motors for power transformers and similar, in accordance with claim 1, wherein the herein claimed system has a motor connect/disconnect (5) control function through serial communication (9), uses only a pair of wires that simply interconnect the communication ports of all motors (2) in parallel, and create a data communication network (4) through which the motors (1) may be controlled without using contactors.

11. A system to control, protect and monitor the status of forced cooling motors for power transformers and similar, in accordance with claim 10, wherein the herein claimed system also allows the receipt of commands to connect/disconnect (5) the motor (1) and send an auto-diagnostic (10) signal, alarms (8) and status (6) (motor connected/disconnected) through an interface communication (7) that uses as means of data transmission its own motor (TC)-input line, and created by such means a data communication network (4) through which the motors (1) may be controlled without using contactors.

12. A system to control, protect and monitor the status of forced cooling motors for power transformers and similar, in accordance with claim 1, wherein the herein claimed system allows the motors (1) to start. or stop individually through a serial communication network (9) without this implying in the involvement of complex wiring and devices.

13. A system to control, protect and monitor the status of forced cooling motors for power transformers and similar, in accordance with claim 12, wherein a motor (1) startup can be performed in a scheduled manner according to the transformer'"'"'s gradual increase in temperature

14. A system to control, protect and monitor the status of forced cooling motors for power transformers and similar, in accordance with claim 1, wherein the proposed system “

in loco”

control is equipped with a keyboard and display (TD) for maintenance and testing purposes.

15. A system to control, protect and monitor the status of forced cooling motors for power transformers and similar, in accordance with claim 1, wherein the measurements (M) made by the proposed system, such as those for voltages and currents during functioning, are useful for monitoring and auto-diagnosis (10) functions, and the motor (1) status monitoring.

16. A system to control, protect and monitor the status of forced cooling motors for power transformers and similar, in accordance with claim 15, wherein the monitoring is performed by calculating the mechanical torque developed by the motor (1) that is already running, from the active electrical power consumed and the motor rotation, measured by a rotation sensor (R) or by taking into account the motor'"'"'s nominal rotation, and the power calculated from the input voltage measurements and electrical current consumed.

17. A system to control, protect and monitor the status of forced cooling motors for power transformers and similar, in accordance with claim 16, wherein the learning stage in which the protection and control system will calculate the motor (1) working torque during the predetermined learning time that may be altered by the user, thus finding the minimum, average and maximum motor torque values, considering that both this and its mechanical load (fan, oil pump, etc.) are in good working order.

18. A system to control, protect and monitor the status of forced cooling motors for power transformers and similar, in accordance with claim 17, wherein the automatic determination of the alarm (8) value per high torque, adding together the predetermined margin of tolerance percentage to the maximum torque working value measured in the learning period.

19. A system to control, protect and monitor the status of forced cooling motors for power transformers and similar, in accordance with claim 18, wherein an alarm (8) per high torque allows detection of mechanical overload in the motor (1), for example, due to lack of lubrication, a pump with an obstructed oil flow or other reasons.

20. A system to control, protect and monitor the status of forced cooling motors for power transformers and similar, in accordance with claim 17, wherein the determination of the alarm (8) value per low-speed torque is automatic, subtracting a predetermined margin of tolerance percentage from the minimum working torque value measured during the learning period. The alarm (8) per low-speed torque allows detection of low mechanical load in the motor (1), for example, due to broken fan blades, breakage in the mechanical connection between the motor and its load and for other reasons.

21. A system to control, protect and monitor the status of forced cooling motors for power transformers and similar, in accordance with claim 16, wherein calculation is performed of the tendency of evolution (increase or decrease) of the torque developed by the motor (1) in an after working for a long time, emitting an alarm (8) in case the calculated tendency reaches maximum and minimum value programmed by the operator, respectively. The alarm (8) per tendency of evolution of the torque allows detection of defects in motor (1) evolution or in its mechanical load still in the initial stage, even before the torque reaches the alarm values per high or low torque.

22. A system to control, protect and monitor the status of forced cooling motors for power transformers and similar, in accordance with claim 15, wherein calculation is performed of the mechanical torque developed by the motor (1) during its start up, from the active electrical power consumed and the motor (1) rotation, measured by a rotation sensor (R) or taking into account the motor'"'"'s (1) nominal rotation, and the power calculated from the input voltage measurements and electrical current consumed.

23. A system to control, protect and monitor the status of forced cooling motors for power transformers and similar, in accordance with claim 22, wherein the protection and control system will calculate in a learning stage the motor'"'"'s (1) start up torque during a number of predetermined start ups that may be altered by the user, thus determining the minimum, average and maximum motor torque value, taking into account that both this as well as its mechanical load (fan, oil pump, etc.) are in good working order.

24. A system to control, protect and monitor the status of forced cooling motors for power transformers and similar, in accordance with claim 23, wherein the alarm (8) value is automatically determined per high start up torque, adding the predetermined margin of tolerance percentage to the maximum start up torque value measured during the learning period. The alarm (8) per high torque allows detection of mechanical overload in the motor (1), for example, due to lack of lubrication, obstructed oil flow in the pump or other reasons.

25. A system to control, protect and monitor the status of forced cooling motors for power transformers and similar, in accordance with claim 23, wherein the alarm (8) value is automatically determined per low start up torque, subtracting the predetermined margin of tolerance percentage from the maximum start up torque value measured during the learning period. The alarm (8) per low torque allows detection of mechanical underload in the motor (1), for example, due to broken fan blades, breakage in the mechanical connection between the motor and its load and for other reasons.

26. A system to control, protect and monitor the status of forced cooling motors for power transformers and similar, in accordance with claim 22, wherein is determined the tendency of evolution (increase or decrease) of the torque developed by the motor (1) after working for a long time, emitted an alarm (8) in case the calculated tendency reaches maximum and minimum values programmed by the operator, respectively. The alarm (8) per tendency of evolution of the torque allows detection of defects in motor (1) evolution or in its mechanical load still in the initial stage, even before the torque reaches the alarm values per high or low torque.

27. A system to control, protect and monitor the status of forced cooling motors for power transformers and similar, in accordance with claim 18, 20, 21 and 25, wherein the alarm values (8) per high or low torque obtained by automatic adjustment may be consulted and manually altered by the operator.

28. A system to control, protect and monitor the status of forced cooling motors for power transformers and similar, in accordance with claim 17, 18, 20, 23, 24 and 25, wherein automatic alarm (8) adjustments per high or low torque may be redone at any time by the system when requested by the operator.

29. A system to control, protect and monitor the status of forced cooling motors for power transformers and similar, in accordance with claim 1, wherein the herein proposed control and protection system comprises an incorporated accelerometer (13) that can measure accelerations in the orthogonal axes due to motor (1) vibrations.

30. A system to control, protect and monitor the status of forced cooling motors for power transformers and similar, in accordance with claim 29, wherein the now “

intelligent”

motor can have incorporated, in an innovative manner, the monitoring of its status by measuring vibrations in such a way that said motor (1) is able to detect and emit alarms (8) due to excessive vibrations caused for example, by unbalances fan blades, defective bearing or other reasons.

31. A system to control, protect and monitor the status of forced cooling motors for power transformers and similar, in accordance with claim 1, wherein the herein proposed system has incorporated a sensor for rotations (R) per minute that can measure the motor'"'"'s rotation speed,

32. A system to control, protect and monitor the status of forced cooling motors for power transformers and similar, in accordance with claim 31, wherein the motor (1) has also incorporated, in a novel manner, the monitoring of its status by measuring its rotation speed.

33. A system to control, protect and monitor the status of forced cooling motors for power transformers and similar, in accordance with claim 1, wherein the herein proposed control and protection system can be applied to other equipment that uses electric motors (1), not only to power transformers, whether these motors function for cooling purposes or for any other functions.