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WSZ700, 800 & 900 SERIES

These power supplies have a thermal time constant of 19 minutes, which means that if a pulsed loading condition exists for a short period of time with respect to 19 minutes, the temperature of the power supply will not rise very much. The following table shows maximum single pulse durations for various average loading conditions.

Please note that the output power is normalized on the table to a factor of 1. This allows the same table to be used for 50W and 60W nominal output models.


Table 1
Period = 30 minutes
Surge Load = 1.33 x Nominal Power Rating

Power Ratio 1,
Low Level
Power Ratio 2,
High Level
Time 1,
Time 2,
Power Ratio
15 min
15 min
18 min
12 min
20 min
10 min
22 min
8 min
24 min
6 min

Diagram 1
Waveform View of Table 1


Since most applications have a more complex current profile with time, a computer program developed here can help analyze the acceptability of any given pulsed loading scenario. To download this program (883KB) click here.

Note, this program will calculate for up to 10 power steps of varying times and amplitudes the peak temperature expected in the transformer, (which is the limiting factor). This program was used to determine the above table.