The common mode voltage (U
cm
) has to be less than ±10 V. It is
reduced by ½ input voltage.
Example: Suppose a voltage source is to be measured which is at a
potential of 120 V to ground. The device itself is grounded. Since
the common mode voltage is greater than permitted,
measurement is not possible. Also, the input voltage difference to
the device ground would be above the upper limit allowed. For
such a task, the C-50xx cannot be used!