The T1 is a four-wire circuit
: two wires for transmit and two wires for receive.
A four-wire circuit
is designed to offer one pair of wires for sending information and another pair for receiving information.
The concept of instantaneous active and reactive power was first elaborated in Japan in 1982, and has been considerably modified since then for three-phase four-wire circuits
, circuits more than three-phase, and power electronics equipment.
The Communications Test award goes to Ameritec for the Model 404, a 3 1/2-lb, 1.544-Mb/s TI/datacom tester as well as an analog transmission impairment tester for two- or four-wire circuits
. Two TX/RX ports support bidirectional drop and insert testing, and the line can be monitored for BERT patterns, ABCD bit status, and SLC alarms.
A new Permanent Series ground fault circuit interrupter is rated for applications up to 30 A and can be configured for 120-V or 240-V, three- or four-wire circuits
. The unit is industrial in construction and carries a NEMA rating of 4X for indoor/outdoor use.
The new data sets operate at rates up to 19.2 kbps over private or leased four-wire circuits
. The modems provide efficient data communication in multistory building and campus environments.