9/15/06
888-2586-001
4-27
WARNING: Disconnect primary power prior to servicing.
Section 4 Overall System Theory
Platinum Z16HD+
Figure 4-11 Simplified Single Phase Power Supply
4.5.1.2.1 Soft Start
A simplified diagram of the Soft-Start and Discharge circuits is shown in Figure 4-12.
During transmitter turn on, a fifth set of SCRs is activated (these are located on the
Rectifier Boards). These SCRs are connected to the lowest voltage output tap of each
transformer secondary (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 about 5 seconds during turn on. After 5 seconds, the soft start
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.
Summary of Contents for Platinum Z16HD+
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