Precision-control-systems 915 Bedienungsanleitung PDF herunterladen (Seite 16)

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Figure 4-4 Conduction of two SCRs connected in reverse parallel when turned on after the beginning of the half-cycles.

The average power a phase angle controller delivers to its load is determined by the number of

electrical degrees by which the gating signal that turns on the SCRs is delayed past the

beginning of the half-cycles. The later in each half-cycle the SCRs fire, the less the time the

SCRs conduct during each half-cycle and, there, the less power is delivered to the load (see

figure 4-5). The o-5 VDC control signal received by the phase angle firing-circuit determines

the amount by which the gating signal is delayed.

INPUT LINE VOLTAGE

FIRING

CIRCUITRY

CONTROL SIGNAL

GATING SIGNAL

OUTPUT LINE VOLTAGE

SCR 1

GATING SIGNAL

SCR 2

SCR 1

SCR 2

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Precision-control-systems 915 Bedienungsanleitung Seite 16