Specifications

Doc Number: VIS-ANA-VER-01001-9002
Date: 27 May 2004
Issue: 5.0
Page: 29 of 80
Author: J. Delgadillo
Controls Preliminary Design Report Issue 5.doc
call out for resetting its Logic Power (single-phase) after an Under Voltage fault occurs
(occurring after removal of 3-phase power). That means that the Logic Power to the
amplifier has to be cycled and the 3-phase CB has to be turned back on in order to clear
(close) an auxiliary switch that the control system is sensing to ensure that the motor
controller is ready for operation. To clarify, not only does the Interlock Chain turn off power
to the amplifiers but also an internal motor controller fault (ie overspeed, over-voltage, under-
voltage, over-current etc) would result in removing 3-phase power to itself. Additionally,
external interlock circuitry to the motor controller ensures that the proper powering sequence
of the motor controllers is maintained.
It should also be mentioned, that regular activation (breaking) of the Interlock chain is highly
not recommended since it compromises the reliability of the system. It’s widely known that
frequent cycling of power to electronic equipment drastically reduces the life of the
equipment. Due to the reliability issue mentioned above, it’s highly recommended that the
Interlock chain not be broken except in emergency or maintenance conditions, as detected by
the mount interlock switches (Emergency stops, Stow Pin Extended, etc).
A second set of the above Interlock contacts is routed over to the LCUs for monitoring
purposes only. A third set of the Interlock contacts is fed to the PDU Control or Status board
for fault reporting and axis disabling. This serves as an added safety level of protection,
satisfying the operational safety spec of AD01 13.4.11.
4.2.4.9 Altitude Manual Drive System
The Altitude axis will have an Auxiliary Manual Drive System (AD01 11.1.12 spec), which
will Interlock the direct drive motors upon activation. The detection method will be via a
switch that senses that the Auxiliary Manual Drive System has been removed from its cradle
position. This would break the Interlock chain and set the Altitude pneumatic brakes. While
in Alt Auxiliary Drive mode, brake release command can only be accomplished by activation
of the Alt Manual Brake Release momentary switch. This would ensure that a minimum of
two persons are involved in the manual movement of the Altitude axis.