Sequence Description - ESAB Esp-1000 Plasmarc System Manual De Instrucciones

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5.2

sequence Description

The program controlling the plasma system sequence is made with the help of a group of conditional states. Inputs from
sensors, and the cutting machine are continuously evaluated by the PLC to determine whether the program stays in its
present state or makes a transition to another state.
The different states are shown as rectangles in Figure 5-2. The function of the seven states are described in the following
paragraphs.
0 - Ready state
The "Ready" state is the normal state for the system to be in when not executing the cutting process. In this state, the system
awaits the start signal from the cutting machine and monitors the selection keys and safety switches. While in this state it
is possible to activate the gas flows for testing and purging the system.
1 - Preflow state
The "Preflow" state is a fixed duration and is reached only from state "0". Nitrogen is always the preflow gas in RUN 1 posi-
tion. Selected cut gas type and flow is the preflow gas in RUN 2 position. Shield Gas also flows during preflow and the air
curtain output is energized at this time.
2 - open circuit Voltage state
The main contactor of the power source is activated after the preflow, and a short time is allowed for the open circuit volt-
age to be reached.
3 - Pilot Arc state
The Pilot Arc State is started by activating the high frequency unit. The time allowed between this and the requirement of
a current flow signal from the power source is a fixed time. If the signal from the power source is not received during this
time, the state is transferred to the Not Ready State 7.
4 - cutting state
In the Cutting State, the cut gas is turned on and the start gas off if using RUN 1. A signal is sent to the cutting machine
control indicating that the process is running. This is the Normal State to be in during cutting.
5 - Priority Postflow state
The Priority Postflow State provides the minimum postflow of nitrogen gas and shield gas flow necessary before a restart
is possible. The time is different depending upon whether cutting with nitrogen or oxygen. This state is reached when the
START / STOP goes low or current flow through the arc is lost.
6 - Final Postflow state
The Final Postflow State provides the time during which nitrogen gas and shield gas flow cools the torch. This state imme-
diately follows the Priority Postflow State, a restart is possible during postflow.
When the time for postflow has elapsed, the program transfers to the 0 Ready State. If a new start signal has been given
from the cutting machine control after it stopped the process, a fast restart will be executed directly from the Postflow State
to State 2 that turns on the main contactor in the power source.
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