Schneider Electric 4000

63230-300-212 Chapter5—Input/Output C apabilities

April 2001 Solid-StateKYZ Pul se Output

Most digitalinputs in energy management systems use onlytwo of the three

wires provided w ith a KYZ pulse ini tiator. This is calle d a 2-wire pulse init iator

application.Figure 5–3 shows a pulse train from a 2-wire pulse initiator

application.

In a 2-wire application,the pulse train looks like the alternating open and

closed statesof a Form-A contact. Most 2-wire pulse initiator applications

usea Form-C contact, but tie into only one side of the Form-C contact where

thepulse is the transition from OFF to ON of that sideof the Form-C relay.In

Figure5–3, the transitions are markedas 1 and 2. Each transition represents

the time when the relaytransitions from KZ to KY. Each time therelay

transitions,the receiver counts a pulse. Thecircuit monitor can deliver up to

25 pulses per second ina 2-wire application.

Figure 5–3: Two-wire pulse train

Some applications requirethe use of all three wires provided with the KYZ

pulse initiator. This is called a 3-wire pulse initiator ap plication. Figure 5–4

shows a pulse train for a 3-wire p ulse initiator application.

Three-wire KYZ pulsesare the transitions between KY and KZ. These

transitionsare the alternate contact closures of a Form-C contact. InFigure

5–4,the transitions are marked as 1, 2, 3, and 4. The receiver countsa pulse

ateach transition. That is, each time the Form-Ccontact changes state from

KY to KZ, or from KZ to KY,the receiver counts a pulse.The circuitmonitor

can deliverup to 50 pulses per second in a 3-wire application.

Figure 5–4: Three-wire pulse train

2-Wire Pulse Initiator

3-Wire Pulse Initiator

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