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Fluke 345
A square wave indicates the polarity shift is virtually instantaneous. This means that all of the energy input is occurring along the top of the square wave thus creating the most advantageous of all pulsing effects. A sloping waveform would indicate current is decreasing during the delivery process.
Pepin recalls one particular troubleshooting prob-
lem when welding issues occurred for an unexplained reason. The welder power supply output was not per- forming as well as needed. Under normal conditions the power supply output should be the square wave form indicating weld current values are switching instan- taneously. One look with the Fluke 345 revealed that under the stressful requirements of thinner wire and high current at the very high frequency required for the application, the power supply was not able to deliver the square wave at this increased demand, but dropped to
a triangular shape. Thus, the current, when being deliv- ered to the weld, was not always at peak value.
“As technology evolves, welders determine if they like the technology. Equipment is set up and all possible data is recorded. Welders must be comfortable with the equipment and it must be user friendly.
Some manufacturers are providing built-in monitoring systems with their welding equipment. But those are often missing information. “We still need the ability to screen capture the waveform image, not just instanta- neous power output to the weld,” Pepin said.
While scopemeters or power quality analyzers may pro- vide more functions, they also provide more complexity than what is needed for the task at hand. With an auto- matic calibration feature and no special leads or complex hook-up requirements, the 345 shows an advantage.
“The portability, the ability to pull something out of the box and put it to use is very valuable,” adds Pepin.
The science of advanced welding technology using complex methods involving welding machine inverter outputs for increasing welding process quality is not simple to understand. Yet the ASME requires certain measurements to ensure welds for pressure vessels and pressure piping meet their intended requirements.
As welders and engineers evaluate new processes and develop welding procedures specific data and wave- forms must be recorded for quality control purposes.
In the event of a problem, the pulsed outputs of current to the weld must be observed and evaluated along with other factors. n
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Close-up of a 345 voltage lead with alligator clip adaptor for ease of application.
By measuring both voltage and current, power levels can be observed and recorded.
Understanding heat input measurements
The Heat Input Measurement has been a long-standing quality control measurement for the welding industry. A fairly simple for- mula, it is volts times amps divided by travel speed. Since voltage times amperage is power, the question answered by the basic for- mula when holding voltage and current values constant becomes: “How much heat are you putting into a length of weld.”
This conventional formula for Heat Input is:
Voltage x Amperage x 60 Travel Speed (in/min or mm/min)
Knowing this is important because heat energy input can affect the characteristics of the weld. As the melting of the base metal and filler metal occur to form the weld, the cross-sectional area of the weld and other metallurgical properties such as tensile strength and hardness are established. Inconsistent arcs or the wrong amount of energy into the weld can cause quality problems.
The AMSE IX allows for calculations using more complex power measurement tools when the waveform is being controlled. If the measurement is in joules (which can also be obtained by conver- sion from watts), then this formula applies for Heat Input:
Energy (Joules)
Weld Bead Length (in or mm)
Power is the rate of energy per unit of time. The Fluke 345 displays power in Watts. For meters displaying this power measurement, this formula applies to determine Heat Input:
Power (or Joules/s if used) x Arc Time Weld Bead Length (in or mm)
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