Electricity: motive power systems – Positional servo systems – Program- or pattern-controlled systems
Reexamination Certificate
2001-02-23
2003-04-29
Nappi, Robert E. (Department: 2837)
Electricity: motive power systems
Positional servo systems
Program- or pattern-controlled systems
C318S567000, C318S568100, C318S600000
Reexamination Certificate
active
06555984
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates electric machines, and more precisely, but not exclusively, to installation procedures of an electric machine to a system comprising means for controlling operation of the electric machine and/or other apparatus connected to the electric machine. The invention relates further to a method of installing an electric machine to a system.
BACKGROUND OF THE INVENTION
Various kinds of electric machines are known. In the industry, the most common electric machine is an alternating current electric motor, such as an asynchronous induction motor or a synchronous motor, providing rotational or linear movement through the output shaft or similar means thereof. The other group of electric machines is formed by generators or alternators providing electricity as output, i.e. accomplishing an opposite electricity-mechanical power transformation. The skilled person is familiar with the general structure, operation, functionality and use of various electric machines, and thus these are not explained in more detail herein.
Normally, the size of an electrical motor is determined by the torque demands and type of the driven device in the system. The system in which the motor is used usually includes various apparatus and components which have to be properly dimensioned and selected relative to each other to avoid any damages caused by improper and unmatching components of the system. For instance, the apparatus of a fixed-speed motor drive such as switches, fuses, contactors, measurement transformers, etc. in the motor starter are selected so that their electrical performance matches the maximal currents, voltages, etc. of the motor.
The motor starters or components thereof may be replaced during maintenance, repair or installation of new equipment to the system. Of course, the size and performance of the replaced or installed components must again match to the size of the motor and/or the other parts and components of the system. It is also possible that the motor or several motors is/are replaced without replacing the motor starter or other components of the system (even if e.g. the motor size changes a little).
Three types of motor starters and feeders which are located in the switchgear are normally used. The fixed motor starter or feeder has relatively low installation cost but when the switchgear has been disconnected from the supply voltage an adding or removing of motor starters or feeders or their components must be performed. Removable motor starter or feeder units can be removed from the equipment compartment when the switchgear is connected. The removable units have plug-in connections to the incoming supply from the distribution bar system in the switchgear, whereas the outgoing cables are connected permanently directly to the apparatus terminals. The electrical connections of a withdrawable type (cassette type) motor starter or feeder are of the plug-in-type which makes its mounting and dismounting very fast. Removable or withdrawable motor starters or feeders are often replaced by another unit during maintenance. It is possible that the replacing unit does not always have equivalent components and thus the quality of motor control or protection may be reduced.
In the case of variable-speed drives, the size and the parameters of the frequency converter installed in the system must be properly selected based on the motor information to ensure correct control and protection of the motor.
The electric machines, and especially electric motors are often protected by a protective device, such as by an electronic protection relay, against e.g. too high voltage or current rates of the system. Before the electric motor is taken into use, the protective device has to be adjusted to take the specific parameters of the particular electric motor into account, so that a correct “level of protection” is defined for that particular electric motor to be protected.
The required parameters are announced by a special label or plate fixedly attached on the motor housing, usually in a position from which it can be readily seen. This label is often referred to as rating (or rate) plate. Sometimes the label is also referred to as value label (or plate) or type label (or plate). Several international and national standards, such as IEC 34-1, have set the minimum amount of information to be disclosed by a rating plate. Usually the parameters in the rating plate include at least the following information: voltage (U), current (I), power (W), cos &psgr; value, frequency (f), and r/min rate. A rating plate may also include some additional information considered as useful and/or necessary. The additional information includes data such as the phase of the motor, the manufacturer, those standards the motor fulfils/according to which it has been constructed, weight of the motor, special conditions for use, etc.
When installing an electric motor, a technician accomplishing the assembly adjusts or configures manually the protective device and/or other control means in accordance with the information he can read from the rating plate. This manual set up and configuration is time consuming and sensitive to human errors. Especially in cases where the motor is to be assembled to form a part of a substantially large system, the losses e.g. in production, and thus the costs for the losses, can become high during this manual configuration work. In addition, the manual configuration involves always a risk for human errors (e.g. a misread of the rating plate, using the rating plate of another motor, an incorrect setting or a “forgotten” and thus undefined parameter).
In addition to the information shown by the rating plate, the control means of a system to which an electric motor has been installed to form a part thereof, may require some additional information to be fed in during the set up and configuration thereof and before the electric motor can be taken into use. This additional information is required especially in cases were condition evaluating and/or overall management and/or control systems are in use. Also frequency converters that supply variable-speed drives need information not normally shown on the rating plate. This additional information may include instructions and parameters for a lubrication system, information concerning the parameters of the bearings installed in the motor, information concerning the thermal behaviour of the motor, information concerning the protection and/or control devices, information concerning maintenance of the motor, etc.
At present this kind of information required by the system algorithm is fed manually to the system, for example by the technicians assembling and configuring the system or the operators using and controlling the system or service personnel accomplishing maintenance or repair to the system. This manual feeding of data involves the same problems as already mentioned above in connection with the manual feeding of the rating plate information.
In the U.S. Pat. No. 5,672,943 (Vivers), “Electronic Control Apparatus”, a separate non-volatile memory for storing the location address of each function unit has been presented. Here, the memory unit is physically associated with each motor such that it is resident in the cabling marshalling area of the motor control centre cubicle. When the control wiring has been fixed, the address information can be transferred from the memory unit of the motor to the control unit, and thereafter it can be used by control unit to retrieve information from a location indicated by said address.
U.S. Pat. No. 5,672,943 disclosure focuses on reading a location address information and getting the data from elsewhere based on this address. U.S. Pat. No. 5,672,943 suggest a memory that suits only for withdrawable cassette-type motor units. It does not suggest any possibility to detect and/or to check that a motor or any other component of the system has been replaced, or that the replaced component can be used in the system. There is no actual suggestion how to set-up the system automatically.
Ikäheimo Jouni
Leskelä Erkki
Makkonen Arto
Rajala Erkki
ABB Oy
Arent Fox Kintner & Plotkin & Kahn, PLLC
Duda Rina I.
Nappi Robert E.
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