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Load Pulse Output

A Definition of Load Pulses
Load Pulses are used to transmit CL&P's meter registration to some other instrument/recorder (either adjacent to or remote from the meter). Load Pulses originate from CL&P's electric meter installed at a customer’s location. Load Pulses are directly proportional to a kilowatt-hour value for that specific customer. The value of the pulse is in terms of energy (kilowatt-hours), not power (kilowatts). A time factor needs to be introduced before the pulse has a value of kilowatts rather than kilowatt-hours (kWh). The industry standard nomenclature for kWh per pulse is Ke. (i.e., Ke = kWh/pulse).

"Form A" Pulse Contact
CL&P Load Pulse meters provide a dry-contact, Form A, 2-wire output circuit for Load Pulses. The 2-wires can provide voltage or current (see maximum input levels, below). They are a make and break contact between the two wires. Two consecutive changes of state represents one kWh per pulse (Ke). That is, when the conductivity changes from "open to closed" and then "closed to open" or from "closed to open" and "open to closed" between the two wires, one Ke of energy has been used.

Specifications
The CL&P standard specifications for Load Pulse outputs are as follows:

  • Form A, 2-wire
  • Dry contact (IE: produces no voltage or current)
  • Maximum Input Voltage: 30 vAC, 38 vDC
  • Input Current Limit: 70 ma., nominal
  • Impedance: 430 ohms
  • Maximum Pulse Rate: 12 pulses/sec.

Meter Interface Enclosure
CL&P provides a Meter Interface Enclosure attached to the customer’s meter socket when Load Pulses are requested by customers/suppliers. The enclosure contains a Load Pulse Output Protector that is also provided by CL&P. Customers/suppliers are responsible for connecting their equipment/recorders to the Form A, 2-wire output of this Load Pulse Output Protector. See a diagram labeled Interface - Load Pulse [PDF:13 KB] .