Functional Principle Of Alternating Current Welding; Fig. 3:Block Diagram Overview: Pst 6000 With Transformer; Fig. 4:Influencing The %I In The Secondary Circuit By Phase Angle - Bosch Rexroth PST 6 Serie Betriebsanleitung

1070087088 / 08 | PST 6xxEx
5.2.2

Functional principle of alternating current welding

U
primary
31°
%I is in­
creased
120
Setting range for
programming
Setting range for
closed-loop controller

Fig. 4:Influencing the %I in the secondary circuit by phase angle

The integrated thyristor power unit controls the AC welding transformer
with a bipolar, sinusoidal voltage with system frequency. In order to in­
fluence the resulting %I in the secondary circuit, the ignition time of the
thyristors is influenced in the positive and negative half-cycle.
PST 6xxx
Control unit
50/60 Hz
U1
V1
Thyristor
power unit

Fig. 3:Block diagram overview: PST 6000 with transformer

Phase angle
130° Degrees electrical
Half cycle of the
mains voltage
%I is re­
duced
-15 Scale divisions
(SKT) %I
Bosch Rexroth AG
Information on this product
AC welding
transformer
U2
V2
Operating principle of PST
corresponds
to low %I
100 0
t
253 / 416
Welding
equipment
corresponds
to high %I
100 0