Weld334m - User’s manual
5
Here below are a few measures which are to be taken in order to avoid harm and damage to
operators and equipment:
1.
Earth the welding transformer secondary.
2.
Install a differential on the welding transformer primary set to the minimum value of
current (30mA).
TRS
Differential/switch unit
380/500V
D
3.
Use a safety device to monitor the value of voltage on the welding guns with respect to
earth. This device should be linked to circuit breaker trip.
380/500V
TRS
V
Voltage sensor
Switch
1.2.3
Current sensor
The current sensor, also known as current coil or Rogowsky coil, thoroid or, sometimes,
more improperly, CT (current transformer), is the device by which the control device
measures and adjusts the welding current during the welding process.
Irrespective of the specifications and standards of the electric transducer characteristics, a
few fundamental rules are however to be applied concerning the position of the transducer
and its relevant wiring. This to minimise errors due to electric and, mainly, magnetic
disturbances.
The reliability and accuracy of the ammeter directly depend on the correct positioning as
well as on the adequate protection against external disturbances.
If the sensor is built into the welding transformer, problems concerning the respect of a few
of the Standards have already been solved in the transformer design phase.
As for sensor positioning, the following requirements are to be adhered to:
•
The sensor is to be located in the welding secondary circuit.
•
The plane to which the sensor is mounted must be orthogonal to the lead run
through by current it measures, that is 90°.
•
The sensor, if external to the welding transformer, must be placed as close as
possible to the welding electrodes. Thus, maximum accuracy is achieved. However,
this mounting position is not always possible. A good compromise lies in mounting
the sensors in the rear part of the guns, near the cable adapter. Provide for
protection against shocks. It can however be always placed at the transformer
secondary output.
To Next Page
Loading...