Precision Control Systems 930 - Manual (Page 18)

Model 930 ControlIR TM Instruction Manual Operating Instructions
Research, Inc. Page 14 of 25
90 ° PHASE ANGLE
360
°
270
°
180
°
90
°
360
°
270
°
180
°
90
°
0
°
MEDIUM POWER
OUTPUT
135
° PHASE ANGLE
360 ° 270 ° 180 ° 90 ° 360 ° 270 ° 180 ° 90 ° 0 °
LOW POWER
OUTPUT
45
° PHASE ANGLE
360 ° 270 ° 180 ° 90 ° 360 ° 270 ° 180 ° 90 ° 0 °
HIGH POWER
OUTPUT
AC PHASE ANGLE
AC LINE VOLTAGE
OUTPUT VOLTAGE TO LOAD
Figure 4-5 Phase angle power
control 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 beginnings 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, therefore, the less
power is delivered to the load (see figure 4-5). The 0–5 VDC control signal received
by the phase angle firing-circuit determines the amount by which the gating signal is
delayed.