Nautel XL12, Technical Instructions

Page: 45 / 238

12 000 WATT AM BROADCAST TRANSMITTER
XL12
Page 2-21
01 January 2002
WARNING
TECHNICAL PRE-COMMISSIONING
2.3
Prior to applying AC power and turning on
the transmitter, some circuits must be customized to
the station's power source and operating
requirements. The following should be completed.
NOTE
Technical pre-commissioning procedures require
technical decisions and customizing of electrical
circuits. They should be incorporated by the
station engineer or a competent electronic
technician.
Reference is made to RF drive and PDM
interphase driver PWBs in the following
procedures. These printed wiring boards are
located on the exciter panel. Refer to figure MD-
1 to locate the exciter panel, to figure MD-6 to
locate the specified PWB and then to the
appropriate PWB service instruction manual for
its assembly detail.
2.3.1 AC POWER SOURCE VARIABLES:
The main power transformer (A23A1T1) and the
low voltage power supply transformer (A23A2T1)
have tapped primary windings to accommodate
variations in the mean voltage level of the AC power
source. Determine and record the AC power
source's nominal, loaded, phase-to-phase, RMS
voltage and then complete the following:
Ensure AC power source is switched off at the
service entrance. If this precaution is not
observed, voltages that may cause serious injury
or death will be present on circuit breaker and
transformer terminals.
2.3.1.1 Main Power Transformer Primary Tap
Selection:
Identify which primary winding taps
should be used and connected to the transformer's
AC power input (H) terminals, as follows:
NOTE
Access to the main power transformer and its
terminals is obtained through the rear door
opening.
(a) Using the voltage recorded as the nominal,
loaded, phase-to-phase, RMS voltage, enter
table 2-1 and determine which primary winding
taps should be selected.
Table 2-1 Primary Winding Taps for A23A1T1
NOMINAL VOLTAGE PRIMARY WINDING TAPS
(RMS, PHASE-TO-PHASE)
178-252 360-505 H1 H2 H3
178-193 360-379 ø1-A ø2-A ø3-A
194-203 380-405 ø1-B ø2-B ø3-B
204-213 406-430 ø1-C ø2-C ø3-C
214-223 431-450 ø1-D ø2-D ø3-D
224-234 451-475 ø1-E ø2-E ø3-E
235-252 476-505 ø1-F ø2-F ø3-F
(b) Verify installed power transformer is rated for
the AC power source voltage by noting voltage
rating on its nameplate.
(c) Connect the moveable wire from each of the
power transformer's input terminals (H1, H2
and H3) to the tap of their associated primary
windings identified in step (a), noting the tap for
all three primary windings must be the same
(A, B, C, etc.).
2.3.1.2 Low Volts Pwr Supply Transformer
Primary Tap Selection:
Identify which primary
winding tap should be used and which terminal on the
DC power supply PWB (A28) should be connected
to its E3 terminal, as follows
NOTE
The primary winding leads from the low voltage
power supply power transformer are routed to
quick-disconnect terminals on the DC power
supply PWB. The appropriate primary winding
tap is selected by interconnecting terminal E3 of
the DC power supply PWB to the appropriate
quick-disconnect terminal
.
(a) Using the voltage recorded as the nominal,
loaded, phase-to-phase, RMS voltage, enter
table 2-2 and determine which quick-
disconnect terminal should be connected to
terminal E3 on the DC power supply PWB.
(b) Interconnect the moveable jumper wire which
originates at terminal E3 to the quick-
disconnect terminal identified in step (a).