×

Monitoring system for use with elongate heater units

  • US 4,667,194 A
  • Filed: 11/02/1984
  • Issued: 05/19/1987
  • Est. Priority Date: 11/02/1984
  • Status: Expired due to Term
First Claim
Patent Images

1. A monitored heating system comprising(1) an AC power supply having a frequency of 50 to 400 hz and(2) a plurality of monitored heating circuits which are connected to the power supply in parallel with each other and each of which comprises(a) an elongate self-regulating heater which comprises(i) two elongate electrodes which are connected to the power supply and each of which has a near end and a far end, the near ends of the electrodes being closer to the power supply than the far ends;

  • and(ii) a plurality of resistive heating elements connected in parallel between the electrodes;

    (b) a transmitter connected to the far end of at least one of the electrodes and capable of transmitting an information signal having a frequency in the range of 10 Khz to 40 Khz along said electrode to the near end thereof; and

    (c) a receiver unit connected to the near end of said electrode for receiving said information signal;

    the transmitters and the receiver units being such that each receiver unit observes the information signal from the transmitter in the same heating circuit but not the information signal from the transmitters in the other heating circuits.

View all claims
  • 3 Assignments
Timeline View
Assignment View
    ×
    ×