PBZ series specifies its rated AC voltage/current as the peak value rather than the RMS value. For example, in PBZ20-20 model, the maximum RMS values are 16.7 V and 16.7 A, not 20 V and 20 A. Therefore, it is necessary to set the “0 to peak” value within the rating.
For the details, read the user’s manual – chapter of Specifications.