Nautel FM10, Технические инструкции, Страница: 106 / 200

10 000 WATT FM BROADCAST TRANSMITTER
FM10
Page 6-5
15 November 1999
de-energized. When the reservoir capacitor has
charged sufficiently so that the voltage at the
(-) input
has dropped to a nominal 5 VDC, a low (near 0.0
VDC) will be applied to the
Pwr Sply Relay Control
output and energize the relay in the associated PA
switching power supply which will short out the
reservoir capacitor's charging resistor and connect the
capacitor
(-) directly to ground. The PDM Inhibit A
signal will switch low (inactive), nominally 4 VDC,
enabling the FET gate drive applied to the PA
switching power supply. Refer to the switching
power supply module service instruction manual for
detailed information.
6.3.7.4 PA Volts Monitor: The PA Volts Sample
outputs from each switching power supply are
individually monitored to see if the voltage either
exceeds the maximum allowable of 55.0 VDC or is
less than the voltage which should be present based
on the pulse duration of the drive applied to the
switching FETs. A sample of the detected PA volts
is applied to the control/monitor PWB [
PA Volts
(Meter) ] at J1-1 for metering purposes.
6.3.7.4.1 High PA Volts: Comparators on the
power supply control PWB monitor the PA Volts
Sample ( A thru F ) inputs for a high condition. If a
PA voltage of 55.0 VDC or greater is detected from
one or more of the switching power supplies, the
PDM
FET Drive signal to the corresponding supply
is inhibited and the Breaker Trip output switches to
0.0 VDC causing the
PWR MDL
circuit breaker to trip
off. The appropriate alarm
PWR SPLY FAIL - PA VDC
LED is turned on and 0.0 VDC is applied to the PA
Volts Alarm output (J11-4), which is applied to the
control/ monitor PWB.
6.3.7.4.2. Low PA Volts: Comparators on the
power supply control PWB monitor the PA Volts
Sample ( A thru F ) inputs for a low condition. A
sample reference of the PA Volts Control input,
proportional to the pulse duration of the switching
FET drive signal, is compared with the
PA Volts
Sample inputs to ensure that switching power
supply's output is proportional to its drive signal. If
the detected
PA Volts Sample is lower than the PDM
voltage reference, the appropriate
PWR SPLY FAIL -
PA VDC
alarm LED is turned on and 0.0 VDC is
applied to the PA Volts Alarm output (J11-4), which
is applied to the control/monitor PWB.
6.3.7.5 IPA Volts Monitor: The IPA Volts
Sample output from IPA switching power supply is
monitored for voltages either in excess of the
maximum allowable of 55.0 VDC or less than the
voltage which should be present based on the pulse
duration of the drive applied to the switching FETs.
A sample of the detected IPA volts is applied to the
control/monitor PWB [
IPA Volts (Meter) ] at J3-4 for
metering purposes.
6.3.7.5.1 High IPA Volts: A comparator on power
supply control PWB monitors the IPA Volts Sample
(J2-3). If an IPA voltage of 55.0 VDC or greater is
detected, the PDM
IPA FET Drive signal to the
supply is inhibited and the Breaker Trip (IPA) output
switches to 0.0 VDC causing
PWR MDL
(
IPA
) breaker
to trip off. The
IPA PWR SPLY FAIL
alarm turns on
and 0.0 VDC is applied to the PA Volts Alarm output
(J11-4), which is applied to the control/monitor
PWB.
6.3.7.5.2 Low IPA Volts: A comparator on the
power supply control PWB monitors the IPA Volts
Sample input. A sample of the IPA Volts Control
input, proportional to the pulse duration of the
switching FET drive signal, is compared to the
IPA
Volts Sample to ensure the IPA switching power
supply output is proportional to its PDM drive
signal. If the
IPA Volts Sample is less than the PDM
reference, the
IPA PWR SPLY FAIL
alarm turns on and
0.0 VDC is applied to PA Volts Alarm output (J11-
4), and applied to the control/monitor PWB.
6.3.7.6 Temperature Monitors: Temperature
sensors in the switching power supplies (A thru F)
and on the 3-phase rectifier assemblies (A2 and A3)
detect high temperature conditions.
6.3.7.6.1 Switching Power Supplies: Each
switching power supply contains a thermistor whose
output is applied to a
Pwr Sply Temp
( A thru F ) input
on power supply control PWB. Comparators on the
power supply control PWB monitor temperature
samples A-F) for a heatsink temperature exceeding
98
°
C. If an excessive temperature is detected from a
switching power supply, the
PDM FET Drive
to the
corresponding supply is inhibited and the Breaker
Trip output switches to 0.0 VDC causing the PWR
MDL
circuit breaker to trip off. The appropriate
PWR
SPLY FAIL - PA
VDC
LED is turned on and 0.0 VDC is
applied to PA Volts Alarm output (J11-4), which is
applied to the control/monitor PWB.