Operating instructions

15
Phase-angle principle VAR (for 1A))
Depending on the prescribed set point, the sine oscillation of the mains voltage is
gated using a larger or smaller control angle . This operating mode is characteri-
zed by high control dynamics.
With phase-angle control harmonics of the mains voltage occur. It is possible to
compensate these by using circuit variants.
Half-wave switch mode QTM (Quick-Takt-Mode for 1A)
QTM is the patented fast operating mode which works on the half wave switch prin-
ciple. Depending on the prescribed set point, mains half waves are switched. D.c.
components are avoided for the phase duration. The fast phase control is particular-
ly suited for IR beams as an alternative to phase-angle control. When using several
controllers it is possible, by synchronisation, to keep the mains reactions small.
2.2 Set point control characteristic
The set point control characteristic of Thyro-A can easily be adapted to the control
output signal of an upstream process controller or automation system. All signals cu-
stomary on the market may be used. The adaption is made by changing the starting
and ending points of the control characteristic.
If the controller is within a limit (U
max
), both red LEDs blink alternatively in second
intervals (chapt. 3.3).
Fig. 1 Control characteristic analog input