Electromagnetic compatibility and electromagnetic interference are important factors of Power engineering and have direct effect on sensitive equipment performance. Therefore, sensitive devices must have field protection against surrounding magnetic fields. This field mitigating mechanism must also prevent any field emitting from the device to the environment. Especially, field mitigation of the magnetic fields created at Power Frequency (PF) is important. In this study fast, simple and direct visible measurements of alternating magnetic field density originating from rotating electrical machines and power lines have been provided. To not disturb the magnetic field distribution, an air core based three orthogonal magnetic coils are used to capture the magnetic flux. The suggested signal conditional circuit can be directly connected to oscilloscope to observe the different components of the magnetic density or can be delivered to some digital circuits to calculate the net magnetic flux vector in the space. The design measurement system has been supported with some measurement examples.