Motorola BLE100 - Manual (Page 17)

2-6 Overview
BLE100 Installation and Operation Manual
Power Supply
The BLE100 power supply is a separate circuit board mounted to the underside of the amplifier
module and is capable of 60 VAC or 90 VAC powering. The power supply provides a regulated
24 VDC output over an AC input between 38 Vrms and 90 Vrms with a line frequency from
50 Hz through 60 Hz. Potentiometer R25 adjusts the output voltage to 24 VDC, however, this is
set at the factory and field adjustment is not recommended.
Figure 2-6 illustrates the components on the power supply.
Figure 2-6
BLE100 power supply
The power supply also contains a two-position LO / HI selector that sets the start-up voltage for
38 VAC or 55 VAC. The BLE100 is shipped with the selector in the LO position which is the
standard configuration. The selector should be switched to the HI position only for a 90 VAC
system. This sets the start-up voltage at 55 VAC. Because this is only 5 V below 60 VAC, it is
not practical in a 60 VAC system. There is no damage to the amplifier if the selector is not
changed from the standard
LO setting. However, changing the selector ensures that the DC
supply does not turn on until the proper input voltage, 38 VAC or 55 VAC, is reached. This
prevents excessive loading of the system power supply during turn-on after a system shutdown.
You must remove the power supply cover to access the selector illustrated in Figure 2-6.
Section 3, “Amplifier Setup” explains changing the setting of this selector to meet system
requirements.
The power supply includes a fast-transfer electronic-crowbar (FTEC) surge protector. The FTEC
is a crowbar circuit that fires at approximately 245 V and presents a short circuit to the line
during periods of overvoltage. After the ac input voltage returns to normal, the FTEC resumes
its open state.
The factory-installed 20-ampere fuse, illustrated in Figure 2-8, provides power-passing to
additional line extenders.