ESAB PEH 4.3, Руководство по обслуживанию, Страница: 19 / 74

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7.3 DC DUO (AP1)
The DC DUO circuit board can be divided into five function blocks:
1. Internal power supply
Generates the necessary power supplies for the electronic circuitry.
2. The processor (IC300)
Controls the motors and communication with the NME circuit board.
The microprocessor controls the motors by measuring their armature voltages,
the available DC bus voltage and the motor currents.
3. Analogue part
Converts the measured quantities from the power section to voltage levels that
allow A/D conversion.
4. Power section
Consists of two full--wave MOSFET transistor bridges and associated drive
circuits and current shunts.
5. Inputs and outputs
For connection of the gas valve, guards, limit switch and the external start/stop
function.
In the interests of a robust system, the heat sinks on which the power
semiconductors are mounted, also carry a thermistor that monitors the temperature
of the heat sinks.
Protection against short circuits is provided by a high--speed overload protection
circuit that shuts down the power section if a short circuit occurs.
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