4-24
888-2586-001
9/15/06
WARNING: Disconnect primary power prior to servicing.
Platinum Z16HD+
Section 4 Overall System Theory
NOTE:
Each power supply is connected to the same PAs as its corresponding PA Con-
troller. For example, PS1 powers the same PAs that are controlled by PA Control-
ler 1. These are listed in Table 4-1 at the end of this section.
Figure 4-8 Simplified 3-Phase Power Supply
4.5.1.1.1 Soft Start
During transmitter turn on, a fifth set of SCRs is activated, see Figure 4-9. These are
connected to the lowest voltage output tap of transformer secondary “B” (the lowest
voltage tap is the one with the fewest secondary turns). However, the Soft Start SCRs
are connected through a common surge limiting resistor to ground, instead of the direct
ground connection provided with the rest of the SCRs. This allows the “Soft Start” by
limiting the maximum surge current while charging the power supplies. The soft start
lasts for 3 - 5 seconds during turn on. After the 3 - 5 second soft start the resistor is
bypassed by activating the normal run-mode SCRs which are also attached to the lowest
voltage output tap but connect directly to ground. This allows the supplies to come up to
full charge. If the voltage is not high enough, the Power Supply Controller will activate
the next highest tap to increase the voltage. It will continue this process until the DC
output voltage is approximately 52Vdc or it reaches the highest tap.
4.5.1.1.2 PA Power Supply Discharge
The PA Power Supply Discharge circuit also uses the Soft Start resistor to discharge the
52Vdc PA supply. The discharge circuit, located on the Rectifier Board, is activated
Содержание Platinum Z16HD+
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