iPAK2 User Guide
35
4.3.3. Current measurement by external toroid (spot weld only)
A toroid (Rogowski coil) is connected around the welding transformer secondary. Most
such coils have a nominal output of 150 mV/kA. The iPAK2 provides a sensitivity parameter
which may be adjusted to provide for absolute matching with an external current meter.
At the nominal 150 mV/kA, iPAK2 will handle signals corresponding to about 50 kA. If the
current is expected to exceed 50 kA then it is necessary to use an attenuator device such
as a TAM/1 between the toroid and iPAK2. The attenuator will have options for x1, x2, x3,
x4 etc. The factor selected should be entered into the iPAK2 so that it is able to calculate
the actual current from the (attenuated) measured current.
In multi-electrode or multi-transformer (cascade) systems it may be difficult to arrange
toroids for multiple secondary circuits. The toroids need to be switched in and out of circuit
at the appropriate moment in the sequence or errors will occur. In these circumstances
use the CT measurement method. The CT method has the advantage of not requiring an
external toroid.
Parameter Units Range Description
Max. primary
current
A 0 - max Limits maximum output
Conversion
method
points/ratio Method used to convert primary current
to secondary current
Turns ratio 1 - 999 The turns ratio of the welding transformer
Point 1 (primary) kA 0 - 32.0 The measured value of primary current at
a low heat (Ip1)
Point 1 (secondary) kA 0 - 500.0 The measured value of secondary
current at a low heat (Is1)
Point 2 (primary) kA 0 - 32.0 The measured value of primary current at
a high heat (Ip2)
Point 2 (secondary) kA 0 - 500.0 The measured value of secondary
current at a high heat (Is2)
Toroid mV/kA 100 - 60000 The sensitivity of the toroid
Toroid factor 1 - 10 The ratio of the external attenuator (1 if
no attenuator fitted)
Blanking time ms 0 - 99 Initial section of a spot weld NOT
included in current measurement.
Default value = 40 ms.
To Next Page
Loading...
