Harris Atlas DVL400, Technical Manual

Page: 131 / 180

2/25/03 888-2473-001 4-31
WARNING: Disconnect primary power prior to servicing.
Section 4 Theory of Operation
ATLAS Series™
4.5 Power Supplies
This section covers both the AC and DC portions of the power supply as well as
control, protection and monitoring. Actual sub-assemblies involved include:
a.
PS (Power Supply) Monitor Board
b.
MOV Board
c.
+32Vdc PA Power Supplies
d. Low Voltage Power Supplies or LVPS
4.5.1 AC Input
The AC mains input comes into the transmitter and attaches to S3, the AC Mains
Disconnect in the front of the transmitter (in Cabinet 1 for DVL 4300 and DVL
5700). This is tied into terminal block TB1 which gives the necessary tie points for
distribution to all of the power supplies (and to the second PA cabinet). Nominal
input voltage is 380, 400, 415VAC for 3 phase and 220, 230, 240VAC for single
phase. Tolerable AC line variation is +10 to -15%.
For 3-phase transmitters, two of the phases are sent to a step-down transformer, T1
to get the 230VAC needed by the exciters, cabinet flushing fans and the low voltage
supplies. For multiple cabinet 3-phase systems, the 230VAC output from T1 is also
sent to the second cabinet, eliminating the need for a second step-down transformer.
Use of the step down transformer also eliminates the need to run a neutral line to the
transmitter in 4 wire WYE systems.
4.5.2 PA Power Supply Modules
The Power Amplifier modules are powered by modular switching power supplies
located in the bottom of the PA Cabinet. One power supply module operates 2 PA
modules. A fully populated PA Cabinet will have 4 power supply modules. The use
of 3-phase or single phase power supplies is determined by transmitter model and is
given in Table 4-1 on page 4-2. The power supplies operate directly from the ac line
with each PS Module having its own circuit breaker on the front of the module.
The power supplies are controlled and monitored by the PS (Power Supply)
Monitor Board. The PS Module DC output can vary from 27 - 33Vdc and is set with
a control voltage from the PS Monitor Board.
In order to optimise the PA efficiency across the entire frequency band (470-
860MHz) the PS Module DC output will depend on the transmitter operating
frequency entered into the GUI Configuration screen. The PS Monitor Board
receives the operating frequency information from the Main Controller which
periodically broadcasts it over the CAN bus.