Electric power distribution system

• US 4,370,562 A
• Filed: 02/25/1981
• Issued: 01/25/1983
• Est. Priority Date: 03/11/1980
• Status: Expired due to Fees

• Current Assignee: Centro Ricerche FIAT SPA Strada Torino An Itaian Joint Stock Company
• Original Assignee: Centro Ricerche FIAT SPA
• Inventors: Palazzetti, Mario, Salotti, Gianfranco
• Primary Examiner(s): GRIFFIN, DONALD
• Application Number:
  US06/237,823
• Time in Patent Office: 699 Days
• Field of Search: 307/11, 307/38, 307/39, 307/31, 307/34
• US Class Current: 307/38
• CPC Class Codes: H02J 2310/60 Limiting power consumption in the network or in one section of the network, e.g. load shedding or peak shaving
• CPC Class Codes: H02J 3/14 by switching loads on to, or off from, network, e.g. progressively balanced loading
• CPC Class Codes: Y02B 70/3225 Demand response systems, e.g. load shedding, peak shaving
• CPC Class Codes: Y04S 20/222 Demand response systems, e.g. load shedding, peak shaving

Abstract

A power distribution system is provided which includes:

a plurality of power outlets connected to the supply conductors of the system and enabling the connection of a corresponding plurality of electrical loads to the system; and

a control unit connected by control conductors to the power outlets and arranged to monitor both the power suppliable by the system and the power required by the electrical loads for their operation.

Each power outlet includes a switching arrangement with two operating states. In its first state, the switching arrangement enables a load connected to the power outlet to be measured by the control unit, this switching arrangement being thereafter switched into its second state by the said control unit to enable the load to be supplied with the power required for its operation only if this power does not exceed the yet-unused electric power capacity of the system.

In one embodiment, each power outlet is arranged to disconnect its associated load on command by the control unit when the system is at the point of becoming overloaded.

Claims

1. An electric power distribution system comprising:

two power supply conductors;

a plurality of power outlet units connected to said two supply conductors whereby to enable the connection to the system of a corresponding plurality of electrical loads;

control conductor means;

a control unit connected by said control conductor means to each said power outlet unit and adapted;

(a) to carry out, at the moment of connection of a said load to a said power outlet unit, a measurement indicative of the increase in power which would need to be supplied by the system to power this load, this measurement being effected in such a manner as to avoid appreciable overloading of the system;

(b) to effect a comparison of the result of said measurement with a measure of the additional power suppliable by the system, and

(c) to provide a comparison-indicative signal indicative of the result of said comparison;

each said power outlet unit including a switching arrangement having two operational states, in the first of which the connection of a said load to said power outlet unit results in the load being inserted between said control conductor means and one of the said supply conductors whereby to enable the control unit to carry out said measurement for that load and effect said comparison, and in the second of which the said switching arrangement connects the load across the two said supply conductors;

change over from said first to said second state occurring only when the comparison-indicative signal provided by the control unit indicates that the power required for the operation of this load will not result in the maximum power suppliable by the system being exceeded,

said control conductor means include a primary control conductor emanating from said control unit and a plurality of further control conductors branching from said primary control conductor and each connected to a respective said power outlet unit, and each said power outlet unit comprising;

first and second input terminals connected respectively to said first and second power supply conductors of the distribution system;

a third input terminal connected to the corresponding said further control conductor;

first and second output terminals to which, in use, an electrical load can be connected;

first and second fixed electrical contacts;

a relay including an excitation winding and a movable contact member, said movable contact member being connected to the said first output terminal and being movable between a working position and a rest position in which it is in contact, respectively, with said first and second contacts, and the said excitation coil of the relay being connected between the third input terminal and the said second contact, and

a hold-on coil connected between said first input terminal and said first fixed contact and operative to maintain the said movable contact member in its working position for the entire period of time during which a said load connected to the power outlet unit is supplied by the said electric power distribution system.

4. A power outlet according to any one of the claims 1, 2 and 3, wherein said excitation coil and said hold-on coil are wound on a common core.

5. A power outlet according to claim 4, wherein said core is a saturable core.

2. An electric power distribution system comprising:

two power supply conductors;

a plurality of power outlet units connected to said two supply conductors whereby to enable the connection to the system of a corresponding plurality of electrical loads;

control conductor means;

a control unit connected by said control conductor means to each said power outlet unit and adapted;

(a) to carry out, at the moment of connection of a said load to a said power outlet unit, a measurement indicative of the increase in power which would need to be supplied by the system to power this load, this measurement being effected in such a manner as to avoid appreciable overloading of the system;

(b) to effect a comparison of the result of said measurement with a measure of the additional power suppliable by the system, and

(c) to provide a comparison-indicative signal indicative of the result of said comparison;

each said power outlet unit including a switching arrangement having two operational states, in the first of which the connection of a said load to said power outlet unit results in the load being inserted between said control conductor means and one of the said supply conductors whereby to enable the control unit to carry out said measurement for that load and effect said comparison, and in the second of which the said switching arrangement connects the load across the two said supply conductors;

change over from said first to said second state occurring only when the comparison-indicative signal provided by the control unit indicates that the power required for the operation of this load will not result in the maximum power suppliable by the system being exceeded,

said control conductor means include a primary control conductor emanating from said control unit and a plurality of further control conductors branching from said primary control conductor and each connected to a respective said power outlet unit, and said further control conductors are connected to earth, and each said power outlet unit comprising;

first and second input terminals connected respectively to said first and second power supply conductors of the distribution system;

a third input terminal connected to the corresponding said further control conductors;

first and second output terminals to which, in use, an electrical load may be connected;

a third output terminal which, in use, is connected to the earth terminal of a load;

first and second electrical contacts fixedly mounted in said power outlet unit;

a third contact connected to said third input terminal;

a relay including an excitation winding and first and second movable contact members;

said first movable contact member being connected to said first output terminal and being movable between a working position and a rest position in which it is in contact respectively with the said first and second contacts;

said second movable contact member being connected to said third output terminal and being fixed to said first contact member, the said second movable contact member being arranged to take up a working position and a rest position in which it respectively enables and prevents the connection of the said third contact to the said third output terminal of the power outlet unit; and

the excitation coil of said relay being connected between the said third input terminal and the said second contact; and

a hold-on coil connected between said first input terminal and said first fixed contact and operative to maintain said movable contact members of the relay in their respective working positions for the entire period of time during which a said load connected to the power outlet unit is supplied by said power distribution system.

3. An electric power distribution system comprising:

two power supply conductors;

a plurality of power outlet units connected to said two supply conductors whereby to enable the connection to the system of a corresponding plurality of electrical loads;

control conductor means;

a control unit connected by said control conductor means to each said power outlet unit and adapted;

(a) to carry out, at the moment of connection of a said load to a said power outlet unit, a measurement indicative of the increase in power which would need to be supplied by the system to power this load, this measurement being effected in such a manner as to avoid appreciable overloading of the system;

(b) to effect a comparison of the result of said measurement with a measure of the additional power suppliable by the system, and

(c) to provide a comparison-indicative signal indicative of the result of said comparison;

each said power outlet unit including a switching arrangement having two operational states, in the first of which the connection of a said load to said power outlet unit results in the load being inserted between said control conductor means and one of the said supply conductors whereby to enable the control unit to carry out said measurement for that load and effect said comparison, and in the second of which the said switching arrangement connects the load across the two said supply conductors;

change over from said first to said second state occurring only when the comparison-indicative signal provided by the control unit indicates that the power required for the operation of this load will not result in the maximum power suppliable by the system being exceeded, said control conductor means include a plurality of control conductors each of which serves to individually connect a respective said power outlet unit to said control unit, and each said power outlet unit comprising;

first and second input terminals connected respectively to said first and second power supply conductors of the distribution system;

a third input terminal connected to the corresponding said control conductor;

first and second output terminals to which, in use, a said electrical load can be connected;

first and second electrical contacts fixedly mounted in said power outlet unit;

a relay including an excitation coil and a movable contact member, said movable contact member being connected to said first output terminal and being movable between a working position and a rest position in which it is in contact respectively with the said first and second contacts, the excitation coil of the said relay being connected between the said third input terminal and the said second contact;

a hold-on coil connected between the said first input terminal and the said first fixed contact and operative to maintain the movable contact member of the said relay in its said working position for the entire period of time during which a said load connected to the power outlet unit is supplied by the said electric power distribution system;

a resistor connected between the said second contact and the said second input terminal of the power outlet unit, the said resistor having a known resistance value higher than that of the maximum load which may be supplied through the power outlet.