WO2000035073A1

WO2000035073A1 - An apparatus for controlling and managing electrically-driven users

Info

Publication number: WO2000035073A1
Application number: PCT/IT1999/000390
Authority: WO
Inventors: Camillo Sansone
Original assignee: Sansone Camillo Di Sansone Camillo
Priority date: 1998-12-04
Filing date: 1999-11-26
Publication date: 2000-06-15
Also published as: IT1304931B1; ITMO980248A1; AU1679700A

Abstract

The apparatus controls and manages electrically-driven users, and comprises: an electrical transformer (1), provided with a plurality of outputs (TM, TS) at various voltages, each of which is connected to an input of a power contactor (2), an output of which contactor (2) is connected to supply phases of a user (5). The apparatus further comprises at least one sensor (4) which detects a parameter connected to an operative state of a user and provides an electrical control signal, proportional to a value of the parameter, to a program logic control (6) of known type which in turn sends in output on-off control signals that actuate opening and closure of the contactors (2).

Description

An Apparatus for Controlling and Managing Electrically-driven Users

Technical Field

The invention relates to an apparatus for controlling and managing users powered by electricity. Background Art

The apparatus which is object of the invention serves to control and manage the operation of one or more users, especially of the types which need very considerable electrical power to operate, but also where the users supplied require only a low-power current.This type of apparatus has a fairly wide field of application: for example (and in no way limitatively), control and start-up of one or more electric motors either together or separately with variation of rotation according to external parameters; control of power supply to lighting groups, with variable flux according to external parameters; control of large heating and conditioning plants according to energetic needs; control of electric machines in industrial automation plants. The prior art for these apparatus comprises, for example, apparatus equipped with variable resistors, current transformers, inverters, electronic card relay transformers, and so on. These apparatus have the following drawbacks. Variable resistors, generally arranged in series to reduce the voltage to the user, are usually controlled by a manual change-over switch. These apparatus have the disadvantage that a considerable quantity of energy is dissipated due to the Joule effect. Furthermore the limit of the electric power which can be regulated is limited to a few KW. These apparatus are also unable to act simply and automatically on a plurality of machines.

Prior art current transformers are manual and can serve one user at a time and manage small wattages, from 20 to 60 KW. Inverters (electronic apparatus which can vary voltage by modifying the frequency) are used exclusively in regulation of the speed of electric motors. A disadvantage of this apparatus is that the controllable powers are limited to about a hundred KW; also, for high wattages inverters are expensive due to the special technology required. A further disadvantage is that the frequency of the energy reaching the user is different from the frequency the user has been designed for, which can lead to overheating and a characteristic buzzing noise. There exist machines equipped with a plurality of inverters functioning in parallel on electric motors, but these too are subject to the power limitations and high costs mentioned above.

Current transformers employing a chip-controlled dedicated electronic card relay have a limitation related to the fact that they can only govern maximum power loads of between 70 to 100 KW. Also, they are used to regulate only one user at a time.

The present invention provides an apparatus which is capable of improving and rationalising user energy consumption while providing users with an automatically-controlled variable voltage according to parameters set by special sensors reading off the variables which are to be controlled.

A further aim of the invention is to provide an apparatus which uses electronic and electro-mechanical components produced in large series and which can be produced in large quantities at reasonable costs. An advantage of the invention is that it can continuously regulate even high- power user apparatus.

A further advantage is that it enables continuous user operation and eliminates the stop and shut-down phases during operation. A further advantage is the greater working life of the users, in that they function optimally and within the limits of the performance which is really required of them.

A further advantage of the invention is to enable control of users, often of different types (motors, lighting systems, heating systems, conditioners, refrigerators and so on) and having various power demands but working in parallel; a most useful invention for the field of industrial plants automation. A further advantage of the invention is that the output voltage can be at the same frequency as the input voltage, enabling the users to work at design frequency. These aims and advantages and more besides are all attained by the present invention, as it is characterised in the appended claims. Disclosure of Invention

Further characteristics and advantages of the present invention will better emerge from the detailed description that follows, of a preferred but not exclusive embodiment thereof, illustrated purely by way of non-limiting example in the accompanying block diagram of the apparatus.

With reference to the block diagram, the apparatus comprises an electric transformer 1, connected in input to the normal electricity supply and provided with a plurality of outputs, denoted by TM and TS, at different voltages. A first part TM of the outputs of the plurality of outputs provides voltages with discrete and constant differences, and a second part TS of the outputs also provides voltages with discrete and constant differences one from the next; the values of which second part TS enable fractional differences to be obtained in the range between one output of the first part TM and the next output of the first part TM. In order to clarify the situation regarding the output voltages, we provide here a practical example. If we wish to control a user apparatus which has a 220-Volt rating in a voltage range which is variable from 140 to 220 Volts, with 4-volt variations, the transformer will have the following output voltages: voltage at the first part TM of the outputs = 140, 160, 180, 200, 220 Volts; voltage at the second part of the outputs = 0, 4, 8, 12, 16 Volts. It will therefore be possible, as will be better explained hereinbelow, to obtain (at the user) voltages which are variable from 140 to 220 Volts with 4- Volt variability.

The size of the transformer, which could be single- or three-phase according to needs, is in accordance with the powers requested by the user apparatus. The apparatus further comprises at least a series of contactors 2 having a switch function, each of which is associated in input with a transformer output. The output of each contactor 2 is connected to the phases of a user 5 electrical supply which, as mentioned above, can be any one of various levels. Each contactor 2 is provided with means for actuating 3 which command the opening and closure of the contactor 2 itself; these means for actuating are substantially constituted by relays, which when excited (as will be further explained herein below) open and close the contactor.

The size of the contactors 2 has to be chosen taking into account the active and reactive potential of the system, in order to ensure a long working life. Contactor sizes are available on the market at sizes of up to 2000 Amps per phase. At present, with a three-phase voltage of 380 Volts, control apparatus can be made having a potential of up to 760 KW, while with a three-phase voltage of 480 Volts (as in the U.S.A., for example) at potential of 960 KW can be achieved. Each user 5 is accompanied by at least one sensor 4 which reads at least one parameter linked to an operative state of the user itself, and sends an electrical control signal which is proportional to the parameter value read. According to which kind of parameter is to be controlled, the sensor (of known type) can be a simple timer, a pH sensor, a redox sensor, a pressure sensor, a light sensor etc. A known-type program logic control 6 is included, for receiving the control signals coming in input from the sensors 4, and for providing in ouput on-off control signals which are sent on to the actuators 3 of the contactors 2 in order to break or close them.

Using a suitable memorised program, the program logic control 6 can process the control signals in arrival from the various users and send the correct command signals for activating the contact actuators.

Various types of program logic controls are available on the market. Obviously when choosing, the number of inputs and outputs necessary for the apparatus functioning will be calculated. Furthermore, should a distance control be desirable, a program logic control will be chosen which has an external communication facility. This could be most useful in some cases, such as, for example, for centralized distance control of public illumination systems. Management and control software installed in the program logic control will be specifically chosen for each single type of user and manages the functions thereof.

The main function is to enable a variation in voltage in output within set parameters. The modus operandi of the apparatus obviously depends on the type of user, so all system variables will be memorized by the program in order to obtain the correct desired operation. For example, if the apparatus is to be used to control a filter plant blower, a pressure sensor 4 will be used to communicate any variation in air pressure inside the pipes with respect to a predetermined pressure value. The program actuates the relays 3 and thus the contactors which will modify the input voltage to the blower and thus change the circulating pressure. The apparatus further comprises a plurality of condensers (or condenser batteries) 7 which can on command be separately connected to the electric mains network which supplies the transformer 1 (on the energy input circuit). The connection of one or more of the condensers is commanded by on-off signals generated by the program logic control 6, which act on connection systems 8 similar to those described herein above, relay-controlled contactors.

The condensers 7 create an automatic power correction system. The control signal for actuating this system is supplied by a sensor 9 arranged on the electrical supply line, which gives the phase difference between the voltage and the current. In the accompanying diagram a user 5 is represented together with its contactor 2 group, while a second user 5' is shown together with some other contactors 2' and the relative relays 3'. As mentioned above, the users can be in any number and of any type, inasmuch as the apparatus operation is represented only by the manageable electrical power.

Device operation will be explained using an example of a single user, but which would be the same (though independent) for each user, and is as follows. Electrical energy is supplied via an input terminal board 10 to the transformer; the various transformer outputs are each connected up to the input of a contactor for each group. The output of each contactor is connected to the phases of the user electrical supply, whose common lines are connected to that of the transformer through a terminal 11. The sensor 4 keeps a constant check on the requests of the external user controlled and sends the control signal on to the input of the program logic control. The control and management software processes the input signal and activates or deactivates the relevant relays which operate the contactors so that each of the contactors can open or close the contact between the output of the transformer which is connected to its input and the supply phases of the user, so as to supply the user, through the output terminal 11 , with the voltage determined by the program logic control. The user supply voltage will be determined by the combination of the voltages supplied by the contactor connected to the TM output actuated and the contactor connected to the TS type output actuated (in the previously-described illustrated example there would be a voltage which was variable from 140 to 220 Volts, with 4- Volt variability). Should automatic phase correction be installed, the software program also calculates the working state of the entire system and activates or deactivates the various dedicated phase correction condensers.

Among other things, the apparatus saves energy; for example, in public lighting systems, where there is no relevant change in lighting conditions, absorbed power will be reduced by 40%. As has been mentioned above, a considerable advantage of the present apparatus is that users of various kinds can all be controlled at the same time but independently.

For a better comparison between the characteristics of the apparatus of the present invention (indicated in the table under "invention") and each of the prior art mentioned in the introduction to the description, a table is provided in which direct comparison is made of the various characteristics and operating parameters, as well as the various operating capacities. From the table it can be seen how the apparatus of the invention resolves problems and offers advantages which none of the prior art is able to do on all counts at once.

Claims

Claims.

l).An apparatus for controlling and managing electrically-driven users, comprising: an electric transformer (1) connected in input to a municipal electricity supply and provided with a plurality of outputs (TM,TS) at various voltages; at least a series of power contactors (2), each of which is associated in input with an outlet of the transformer (1) and in output with the supply phases of a user (5), each of said series of power contactors (2) being provided with means for actuating (3) which control opening and closure thereof; at least one sensor (4) for each user (5), for detecting at least one parameter connected with an operating state of a user, and for sending an electrical control signal proportional to a detected parameter value; a program logic control (6) of known type for receiving in input the electric control signal coming from the sensor (4) and for providing in output on-off control signals which are sent on to the means for actuating (3) the contactors (2). 2). The apparatus of claim 1, characterised in that: a first part (TM) of the plurality of outputs (TM, TS) provides voltages having discrete differences of a constant entity; a second part (TS) of the plurality of outputs (TM, TS) provides voltages having discrete difference of a constant entity; the values of which second part (TS) enable fractional differences to be obtained in a range between one output of the first part (TM) and a next output of the first part (TM).

3). The apparatus of claim 1, characterised in that it comprises a plurality of condensers (7) which can be connected on command and independently to the municipal electricity supply which supplies the transformer (1); a connection of one or more of the condensers (7) being commanded by on-off command signals generated by the program logic control (6).

4). The apparatus of claim 1, characterised in that the program logic control (6) is provided with an external communication port for receiving remote control signals.