User's Manual

SBS-900 Shore Based Radar Systems
Chapter 9: Planned maintenance
KH-1602-2 issue 1: Standard SBS900 Systems Operator & Maintenance Handbook
Page 112 of 240
5-year maintenance: Changing the static inverter in the RDU
Inspection sheet
6 of 6
Measuring the three phase output
The three phase output of the inverter is a pulse width modulated (PWM) sine wave which cannot be
accurately measured using a standard DVM (Digital voltmeter).
If measured the 440VAC output will actually measure approximately 220VAC +/-10% depending on
the multimeter being used.
Completion of task
On completion of the inverter commissioning, switch the system OFF and reconnect the three-phase
output to the antenna motor (PL4 on the base of the RDU).
Switch the system ON and ensure that the inverter is operational and that the antenna is rotating.
When operational, the inverter will have the following status:
' The charge light will be ON
' The Run indicator will be ON
' The display will show 22Hz for 20RPM systems and 44Hz for 40 RPM systems.
With the inverter ON and the antenna rotation and man aloft switches are in the FREE position the
antenna should rotate.
Remote control operation
When the inverter and fan replacement is completed, ensure that the Local/ Remote switch on the
Radar Distribution Unit (RDU) is in the Remote position.
Ensure that the system can be remotely controlled and is fully operation.