2-4 Electric Drives
and Controls
Bosch Rexroth AG PSI 6500.xxx 1070087059 / 02
Fundamentals on the Master-Slave Mode
2.2 How to Use Current Sensors
Some special items must be observed in the master-slave mode when
actual currents are measured.
1. Actual currents may only and exclusively be controlled or moni-
tored by the master! For that reason,
D the slaves must transfer the measurement values of their primary cir-
cuit current sensor to the master; the slaves transfer this information
via the connection cable at X6;
D secondary circuit current sensors must always be connected to the
toroid-input
of the master (X3, terminals 1 and 2; see page 3-2).
2. The position and number of the current sensors in the secon-
dary circuit are dependent on each other! Observe the following:
D If only one current sensor is used in the secondary circuit, its measu-
rement value must be proportional to the welding current.
D If several current sensors are used in the secondary circuit, the total
of their measurement values must be proportional with the welding
current. Here, the following applies:
- all sensors must have the same sensitivity,
- all sensors must be connected in series, and
- the output voltages of the sensors must always have the same
sign.
Power
section
Master
PSG
Power
section
Slave 1
Control
module
Con-
nection
logic
Power
section
Slave 2
Con-
nection
logic
PSG
PSG
Primary
current
sensor
PSI
PSI
PSI
Primary
current
sensor
Primary
current
sensor
Electrodes
All PSGs are
connected in
parallel.
X7
X6
X7
X6
Master-slave mode when the primary current sensors integrated in the PSI are used
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