The maximum voltage measuring range of the Chroma 66203/66204/66205 digital power meters is 600 mVrms (CF=2). If the voltage to be measured is greater than this specified measuring range, the voltage range for the two power meters can be extended to 1800V using the upstream measuring accessory A662023. However, in this case the frequency is limited to DC and 47 to 63 Hz. To ensure the specifications, the power meters 66203 and 66204 must be used together with the A662023. One A662023 is required for each measuring channel of the power meters.