LORCH P-Basic - Monitoring Welding Current

Troubleshooting
- 50 - 02.20909.2710.1-06
9.3 Monitoring welding current
The welding current is measured via a separate current sensor (VAC). The current is monitored by the
Microcontroller (Master) and the DSP (Process) independantly from each other.
Schematic
1
2
3
4
current
sensor
DCDRV
X2 / 2
X2 / 1
X2 / 3
X1 / 16
X1 / 15
X1 / 14
MAPRO
+15V
-15V
MASTER
DSP
+3.3V
Fig. 40: Measuring welding current
The output of the current sensor is a current with a ratio of 1:2000, meaning at a welding current of 300A
the sensor output is 150mA. The output current is measured via an internal shunt resistor by the Master
and Process (independant measurings).
If the Master measures a current >120% of the maximum value, the machine will stop and displays E03
(secondary overcurrent). For example the maximum welding current of a Saprom S5 is 400A, if the Master
measures a welding current > 480A, it stops with E03.
If the Master measures a voltage >3.5V at the shunt resistor (that would mean a welding current >988A),
the machine will stop and displays E09 (error v/a measuring).
If the Process is measuring a welding current >20A although the machine is not welding (standby), the
machine will stop and displays E21 (Output voltage/current).