Electronic demand register

• US 4,571,692 A
• Filed: 04/12/1984
• Issued: 02/18/1986
• Est. Priority Date: 04/12/1984
• Status: Expired due to Term

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Germer, Warren R.
• Primary Examiner(s): Gruber, Felix D.
• Assistant Examiner(s): Herndon, Heather R.
• Application Number:
  US06/599,684
• Time in Patent Office: 677 Days
• Field of Search: 364/482, 364/483, 364/492, 364/493, 364/480, 364/141, 364/184, 364/900 MS File, 324/103 R, 324/116
• US Class Current: 702/60
• CPC Class Codes: G01R 11/64 Maximum meters, e.g. tariff for a period is based on maximum demand within that period
• CPC Class Codes: G01R 21/1338 Measuring maximum demand

Abstract

An electronic demand register includes a processor for calculating a demand in a demand subinterval. At the end of each demand subinterval, the calculated demand is summed with the demand in the preceding N-1 subintervals to derive an interval demand over N contiguous subintervals. The interval demand is compared to a previously recorded maximum demand and, if the interval demand exceeds the maximum demand, its value is substituted for the maximum demand for use in subsequent comparisons. The processor employs volatile memory. A non-volatile memory is provided for storing the billing data and programmed constants in the event of an impending power outage. A power monitor detects the possibility of an impending power outage and, operating on stored energy, both enables and powers the transfer of data to the non-volatile memory. When power is resumed, the power monitor enables resetting the processor and retransferring the data from the non-volatile to the volatile memory for resumption of demand metering. A grace period is provided after the resumption of power before beginning demand metering to permit the energy user'"'"'s starting loads to pass before demand metering begins. Provision is made for treating the beginning and ending of a test operating mode similar to a power outage. In addition, the demand register responds to its removal from, and its replacement in, the electric meter in a manner similar to its response to a power outage.

Claims

1. A demand register for an electric meter comprising:

a processor;

means in said processor for calculating a rolling demand including means for summing a demand in a subinterval with demands in a preceding N-1 subintervals to derive an interval demand over N contiguous subintervals;

means for storing a maximum demand;

means for replacing said maximum demand with said interval demand if said interval demand exceeds said maximum demand;

said processor including a volatile memory;

a non-volatile memory;

means responsive to a predetermined reduction in a voltage fed to said electric meter for enabling a first transfer of at least said maximum demand, a value representing a time at which a subinterval is interrupted by said predetermined reduction in said voltage and a plurality of programmed constants from said volatile memory to said non-volatile memory;

means responsive to a predetermined restoration in a voltage fed to said electric meter for enabling a second transfer of said maximum demand, said value and said plurality of constants from said non-volatile memory to said volatile memory; and

means for resuming operation of said demand register following said second transfer at a time in a first subinterval corresponding to a time represented by said value.

2. A demand register according to claim 1 wherein said means for resuming operation includes means for providing a grace period following said second transfer during which a start of demand metering is delayed.

3. A demand register according to claim 1, further comprising means for changing a functional operation of said demand register between a first operation and a second operation, said means for changing a functional operation including means for enabling said first transfer in response to changing said functional operation from said first operation to said second operation and for enabling said second transfer in response to changing said functional operation from said second operation to said first operation.

4. A demand register according to claim 3 wherein said means for resuming operation includes means for providing a grace period following said second transfer during which a start of demand metering is delayed.

5. A demand register according to claim 1 wherein a data protocol for communication between said volatile memory and said non-volatile memory is incompatible, further comprising:

formatting a first data message for transmission from said volatile memory to said non-volatile memory containing at least a leading portion which said non-volatile memory ignores, a remainder of said first data message including a data protocol which said non-volatile memory is capable of accepting; and

processing a second data message received in said volatile memory from said non-volatile memory by at leasst a selective shift and an ignoring of at least part of said second data whereby a remainder of said second data message includes a data protocol which said volatile memory is capable of accepting.

6. A demand register according to claim 1 further comprising:

means for copying data from a non-volatile memory of a first demand register which has been removed from said electric meter to a second demand register before it is installed in said electric meter;

said means for copying including means in said first demand register for recognizing a removal of said first demand register as the equivalent of an impending power outage and for transferring data from said volatile memory to a first non-volatile memory in said first demand register;

said means for copying further including a programmer;

said programmer including means for reading a content of said first non-volatile memory and for temporarily storing said content;

said programmer further including means for writing said content into a second non-volatile memory in said second demand register; and

means in said demand register for recognizing an installation of said second demand register in said electric meter as the equivalent of a resumption of said voltage to said electric meter whereby said second transfer from said non-volatile memory to said volatile memory is performed and normal operation of said electric meter including said second demand register is resumed.

7. A demand register for an electric meter comprising:

a processor;

means in said processor for calculating a rolling demand including means for summing a demand in a subinterval with demands in a preceding N-1 subintervals to derive an interval demand over N contiguous subintervals;

means for storing a maximum demand;

means for replacing said maximum demand with said interval demand if said interval demand exceeds said maximum demand;

said processor including a volatile memory;

a non-volatile memory;

means responsive to a predetermined reduction in a voltage fed to said electric meter for enabling a first transfer of at least said maximum demand, a value representing a time at which a subinterval is interrupted by said predetermined reduction in said voltage and a plurality of programmed constants from said volatile memory to said non-volatile memory;

means responsive to a predetermined restoration in a voltage fed to said electric meter for enabling a second transfer of said maximum demand, said value and said plurality of constants from said non-volatile memory to said volatile memory;

means for resuming operation of said demand register following said second transfer at a time in a first subinterval corresponding to a time represented by said value;

means for changing a functional operation of said demand register between a first operation and a second operation;

said means for changing a functional operation including means for enabling said first transfer in response to changing said functional operation from said first operation to said second operation and for enabling said second transfer in response to changing said functional operation from said second operation to said first operation;

said means for resuming operation including means for providing a grace period following at least some of said second transfers during which a start of demand metering is delayed;

a data protocol for communication between said volatile memory and said non-volatile memory being incompatible;

means for formatting a first data message for transmission from said volatile memory to said non-volatile memory containing at least a leading portion which said non-volatile memory ignores, a remainder of said first data message including a data protocol which said non-volatile memory is capable of accepting;

means for processing a second data message received in said volatile memory from said non-volatile memory by at least a selective shift and an ignoring of at least part of said second data whereby a remainder of said second data message includes a data protocol which said volatile memory is capable of accepting;

means for copying data from a non-volatile memory of a first demand register which has been removed from said electric meter to a second demand register before it is installed in said electric meter;

said means for copying including means in said first demand register for recognizing a removal of said first demand register as the equivalent of an impending power outage and for transferring data from said volatile memory to a first non-volatile memory in said first demand register;

said means for copying further including a programmer;

said programmer including means for reading a content of said first non-volatile memory and for temporarily storing said content;

said programmer further including means for writing said content into a second non-volatile memory in said second demand register;

and means in said second demand register for recognizing an installation of said second demand register in said electric meter as the equivalent of a resumption of said voltage to said electric meter whereby said second transfer from said non-volatile memory to said volatile memory is performed and normal operation of said electric meter including said second demand register is resumed.