9/15/06
888-2586-001
4-35
WARNING: Disconnect primary power prior to servicing.
Section 4 Overall System Theory
Platinum Z16HD+
4.6.2.1
Rectifier Board
The SCRs for the single phase are required to carry a much larger amount of current
than the 3-Phase counterparts and are therefore much larger. They are mounted on large
heatsinks on top of the transformers. The SCRs are used for the tap switching,
rectification of the AC voltage and as switches to turn the power supplies on and off.
Each transformer secondary winding has 8 taps. Each of these taps have one SCR to
ground. The secondary is full wave rectified, which means that one SCR on each side of
the center tap is used for each voltage level. For example CR1 and CR5 on either
transformer will be active at the same time. The other pairs are CR2 and CR6, CR3 and
CR7 and CR4 and CR8. The Power Supply Controller can turn on any pair of the SCRs
at a given time. If the voltage is not high enough at the DC output, the PS Controller can
change the transformer turns ratio by turning on a different SCR pair and therefore
utilizing a different secondary tap. The taps closest to the center will provide the least
amount of secondary turns in circuit and will therefore give the lowest DC output
voltage. This means that the taps which are furthest from the center will give the highest
DC output voltage due to more active turns in the secondary. The DC voltage range
with a nominal AC input voltage is 48 - 54Vdc.
4.6.2.2
Rectifier Board Circuit Description
Refer to the Rectifier Board schematic for the following. The Rectifier Boards perform
3 primary functions:
•
Dynamic secondary tap switching using SCRs. This maintains a relatively constant
supply voltage and thus maintains constant transmitter power output despite fluctua-
tions in the AC line voltage.
•
PA Power Supply Soft-Start.
•
PA Power supply Discharge.
4.6.2.2.1 Tap Switching Circuit Operation
The control signals for the SCRs are active high and come directly from the PS
Controller Board. They enter the Rectifier Board at:
•
J4-1 - DRIVER 1 = TAP 1 (activates SCRs for 48V tap)
•
J4-3 - DRIVER 2 = TAP 2 (activates SCRs for 50V tap)
•
J4-5 - DRIVER 3 = TAP 3 (activates SCRs for 52V tap)
•
J4-7 - DRIVER 4 = TAP 4 (activates SCRs for 54V tap)
NOTE:
The circuit for the 48V tap will be explained here as the other three are identical,
but are attached to different transformer taps.
Содержание Platinum Z16HD+
Страница 4: ...MRH 2 888 2586 001 9 15 06 WARNING Disconnect primary power prior to servicing ...
Страница 6: ...9 15 06 888 2586 001 MRH 1 WARNING Disconnect primary power prior to servicing ...
Страница 8: ...viii 888 2586 001 9 15 06 WARNING Disconnect primary power prior to servicing ...
Страница 10: ...x 888 2586 001 9 15 06 WARNING Disconnect primary power prior to servicing ...