High Current Measurements

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There are several ways to measure current with the Mooshimeter. This page collects best practices and recommended equipment for different kinds of measurements.

Internal Measurement[edit]

The Mooshimeter can measure current directly between the A and C terminals. The fuse supplied with the Mooshimeter will blow at 12A, so the current you're measuring must be less than this.

External Shunt[edit]

The Mooshimeter's auxiliary input (labelled Ω) has extremely high resolution for measuring small voltages, which makes it well suited for measuring the voltage drop across an external shunt resistor, which is typically in the +-100mV range. Current shunts are usually labeled with either their resistance or their voltage drop at a specific current. For example, this shunt is labeled "100A/75mV", which means that if you read a 75mV voltage across the shunt, you can deduce that 100A is flowing through it.

External Current Transducer[edit]

Some current transducersproduce a reading without sitting in the path of the current being measured. Both of these produce a voltage output and can be measured on the Mooshimeter's auxiliary input (labelled Ω). There are two main types, detailed below.

DC/Hall Effect Type[edit]

These transducers produce a voltage proportional to the measured current. The ratio will usually be listed on the device itself, for example on the Mastech CA100 the ratio is 1mV/A, meaning that if you read 10mV at the output, a current of 10A is passing through the clamp. This type of clamp is battery powered and can be used for AC or DC current.

AC/Current Transformer Type[edit]

This type of transducer can be used in the same way as the Hall effect type listed above, except that it is only useful for AC current. Since it has only passive components it requires no batteries.