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Principle & Technical data
WP 120A Block diagram of principle
3~380V/50Hz
Figure 1: Block diagram of principle
This series of cutting machines applies IGBT Middle Frequency inverter technology. Line
frequency 3-phase input volt are rectified by rectifier, inverted into MF AC by IGBT components,
insulated by MF transformer, rectified and filtered by MF rectifier, then outputs DC power
suitable for cutting. After this process, the cutter’s dynamically responsive speed has been greatly
increased, so the transformer and reactor size and weight are reduced noticeably, thus achieving
energy-saving.
Power sources enjoy sound drooping outer ability and anti-fluctuating ability due to loop control
of reasonable logic circuit design. First, the signals of the set parameters transmit into set circuit
to adjust output current. Secondly, the feedback circuit amplifies output current to get feedback
signal. PWM circuit compares the set signals with feedback signals to determine output pulse
width. Finally, driving circuit will control pulse to amplify power to drive IGBT. Meanwhile,
protection circuit monitor over-current, low-voltage and overheat phenomenon to ensure reliable
cutting. Because of reasonable sequence of logic control, the cutters can perform pre-gas flow,
HF arc start, cutting and post-gas flow convenient for operators.
U0
I2min I2max
Figure 2: Model WP 120A Volt-Ampere curve
Rectifier
MF
Inverter
MF
Transformer
Rectifier &
Filter
Control circuit
High frequency arc start
U
（
V
）
I(A)
