Programmable demand register with two way communication through an optical port and external reading devices associated therewith

A programmable demand register (PDR) for registering AC electric energy consumption by a load comprising:

• energy flow pick-up means being responsive to the field created by the secondary coil of the PDR in the standard manner, the improvement comprising:
• secondary coil input impedance compensation means including,
• a bridge circuit connected so that, under stable voltage conditions, circuit current remains stable, and with voltage increase the circuit current also rises, and with voltage decrease the circuit current also decreases, and whereby all the three aforesaid conditions present the same input impedance to the said secordary coil;
• optical scanning means including light emitting and light receiving sources, completion of light transmission therebetween being periodically interrupted by said energy flow pick-up means;
• a transducer responsive to the transmit-non transmit mode of said optical scanner means to produce a binary code output which is directly related to electric energy consumption and which is stored in a first memory;
• clock means producing real time data;
• a second memory containing program control data;
• bidirectional optical communication port means;
• PDR data output means whereby, upon receipt of a signal, the data stored in said first memory is transmitted to a receiver external of the PDR;
• and
• PDR data input means whereby the meter memories may, upon receipt of a proper password signal, be actuated.