Method and system of selective disconnection of loads from a power source

• US 4,208,593 A
• Filed: 02/13/1978
• Issued: 06/17/1980
• Est. Priority Date: 02/13/1978
• Status: Expired due to Term

• Current Assignee: Energy Conversion Devices
• Original Assignee: Energy Conversion Devices
• Inventors: Sullivan, Matthew D.
• Primary Examiner(s): Gellner, Michael L.
• Assistant Examiner(s): Schneyer, S.D.
• Application Number:
  US05/877,317
• Time in Patent Office: 855 Days
• Field of Search: 307/64, 307/35, 307/34, 307/39, 307/126, 307/130, 307/149, 307/62, 307/141.4, 307/23, 307/24, 307/29, 364/105, 364/119, 364/492
• US Class Current: 307/35
• CPC Class Codes: H02H 3/033 with several disconnections in a preferential order, e.g. following priority of the users, load repartitionH02H3/06 takes precedence
• 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 method and system for controlling peak electrical demand placed on a source of electrical energy by a plurality of electrical loads that include at least one electrical load of lower priority than at least another of the loads. Demand for electrical energy by the loads connected to the source of electrical energy is sensed and, in response to the sensed demand exceeding a predetermined value the loads are selectively disconnected from the source. Normally, all the loads are connected to the source in the absence of a sensed excessive demand condition. Therefore, all demand control is lost in the event of failure of the controller. Accordingly, the system senses an abnormal operating condition of the controlling system of the type that renders the selective disconnecting means inoperative to disconnect the loads from the source. The electrical load of lower priority is then disconnected from the source for the duration of the sensed abnormal condition. Also disclosed are a system and method for selectively disconnecting loads from a source on the basis of either demand and time or merely demand.

Claims

1. A system for controlling the disconnection of a load from a source of power as a function of a predetermined condition relating to power usage and as a function of time, the system comprising:

means connected to the load for selectively disconnecting the load from the source of power in response to a control signal assuming a disconnecting value;

a source of a first control signal that selectively assumes said disconnecting value in response to the predetermined condition;

a source of a second control signal that is fixed at said disconnecting value;

timing means for generating an enabling signal indicating a predetermined time period;

selector means for selecting between first and second modes of operation of said system;

switching means connected to said selective disconnecting means and said selector means, said switching means receiving said first and second control signals and said enabling signal, said switching means applying said first control signal to said disconnecting means in response to said selector means selecting either of said first or second modes of operation and said enabling signal indicating a time outside said predetermined time period, said switching means applying said first control signal to said disconnecting means in response to said selector means selecting a predetermined one of said first and second modes of operation and said enabling signal indicating a time within or outside said predetermined time period, said switching means applying said second control signal to said disconnecting means in response to said selector means selecting the other of said first and second modes of operation and said enabling signal indicating a time within said predetermined time period, whereby the load is disconnected from the source during the entirety of said predetermined time period when said selector means selects said other of the modes and is selectively disconnected in response to said predetermined condition at all times outside said time period as well as at times during said time period when the selector means selects said one of the modes.

2. The system of claim 1 wherein said selector means is a manually operable means for positioning the contacts of a switch and said switching means includes normally open and normally closed switch contacts having a common contact, the first control signal being supplied to the common contact through the normally closed contact and the second control signal being supplied to the common contact through the normally open contact, the normally closed contact assuming a closed position and the normally open contact assuming an open position with said selector means selecting said one of the modes of operation.

3. The system of claim 1 including means for sensing an abnormal operating condition of the controlling system that renders the selective disconnecting means inoperative to selectively disconnect the loads from the source, and for effecting the disconnection from the source of at least one load of lower priority than another load in response to the sensed abnormal condition.

4. A method for controlling the disconnection of a load from a source of power as a function of two different predetermined conditions including time comprising the steps of:

selectively disconnecting the load from the source of power in response to a control signal assuming a disconnecting value;

supplying a first control signal that selectively assumes a disconnecting value in response to the predetermined condition;

supplying a second control signal that is fixed at said disconnecting value;

generating an enabling signal indicating a predetermined time period;

selecting between first and second modes of operation of said system wherein the second mode is a timed mode;

controlling the disconnection of the load from the source in response to the first control signal when either of the first or second modes of operation is selected and the enabling signal indicates a time outside the predetermined time period and when the first modes of operation is selected and the enabling signal indicates a time within or outside the predetermined time period; and

,

controlling the disconnection of the load from the source in response to the second control signal when the second mode of operation is selected and the enabling signal indicates a time within the predetermined time period, whereby the load is disconnected from the source during the entirety of said predetermined time period when said selector means selects said other of the modes and is selectively disconnected in response to said predetermined condition at all times outside said time period as well as at times during said time period when the selector means selects said one of the modes.

5. A system for controlling the selective disconnection of a load from a source of power as a function of a predetermined condition relating to power usage, the sensing of an abnormal condition, or a function of time, the system comprising:

a source of a first control signal that selectively assumes a disconnecting value in response to a demand for electrical power exceeding a predetermined value;

means connected to the load for selectively disconnecting the load from the source of power in response to the control signal assuming the disconnecting value;

a source of a second control signal that is fixed at said disconnecting value;

timing means for generating an enabling signal indicating a predetermined time period;

selector means for selecting between first and second modes of operation of said system;

switching means connected to said selective disconnecting means and said selector means, said switching means receiving said first and second control signals and said enabling signal, said switching means applying said first control signal to said disconnecting means in response to said selector means selecting either of said first or second modes of operation and said enabling signal indicating a time outside said predetermined time period, said switching means applying said first control signal to said disconnecting means in response to said selector means selecting a predetermined one of said first and second modes of operation and enabling signal indicating a time within or outside said predetermined time period, said switching means applying said second control signal to said disconnecting means in response to said selector means selecting the other of said first and second modes of operation and said enabling signal indicating a time within said predetermined time period, whereby the load is disconnected from the source during the entirety of said predetermined time period when said selector means selects said other of the modes and is selectively disconnected in response to the demand for electrical power at all times outside said time period as well as at times during said time period when the selector means selects said one of the modes; and

means for sensing an abnormal operating condition of said controlling system that renders the selective disconnecting means inoperative to selectively disconnect the load from the source, and for disconnecting the load from the source in response to the sensed abnormal operating condition.

6. A method for controlling the selective disconnection of a plurality of loads from a source of power as a function of three different predetermined conditions including time comprising the steps of:

supplying a first control signal that selectively assumes a disconnecting value in response to one of the predetermined conditions;

selectively disconnecting at least one of the loads from the source of power in response to the control signal assuming the disconnecting value;

supplying a second control signal that is fixed at said disconnecting value;

generating an enabling signal indicating a predetermined time period;

selecting between first and second modes of operation of said system wherein the second mode is a timed mode;

controlling the disconnection of the load from the source in response to the first control signal when either of the first or second modes of operation is selected and the enabling signal indicates a time outside the predetermined time period and when the first mode of operation is selected and the enabling signal indicates a time within or outside the predetermined time period;

controlling the disconnection of the load from the source in response to the second control signal when the second mode of operation is selected and the enabling signal indicates a time within the predetermined time period, whereby the load is disconnected from the source during the entirety of said predetermined time period when said selector means selects said other of the modes and is selectively disconnected in response to said one predetermined condition at all times outside said time period as well as at times during said time period when the selector means selects said one of the modes;

sensing an abnormal operating condition of said controlling system that prevents the selective disconnecting of the loads from the source; and

disconnecting from the source at least one of the electrical loads of lower priority than another one of the electrical loads in response to the sensed abnormal operating condition.