Solution
The primary windings must be connected in seric
because the normal voltage should be 480 V. Therefon
check the transformer nameplate for series tap conne<
tions. Move down the voltage column until the actu:
input voltage fits between two numbers. Usually, th
higher voltage on the chart is used. If the lower numbt
is used, the output will be greater than 240 V. Tr
proper connection is shown in Figure 14-20 with
jumper wire placed between taps 5 and 6. If the input he
been 480 V, the jumper would have been between taps
and 4.
Assume that the input is 225 V and the desired output is 120 V. This requires the primary winding to l .
placed in parallel. This time, the parallel high-voltage
tap connection chart on the nameplate is used. Mark tllocation on the chart where the actual input voltage fit
Then take the next higher tap connection on the chm
Figure 14-21 shows the proper connection.