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                VARIABLE SPEED DRIVE

Purpose. Install one motor and variable speed drive (VSD) system on
the Nimitz class aircraft carrier 36-inch warping capstan
application. The capstans are Class 1 (in accordance with
MIL-C-17944, as amended), mounted on the 02 level forward and main
deck aft with motor and reduction gear mounted on deck below. Provide
complete system in accordance with the attached general specification
requirements motor and drive. Exceptions to the general requirements
shall be obtained from NNS in writing prior to effecting the change.
This first “proof-of-concept” PMB motor and drive will be used for
evaluation purposes and installed either at Newport News Shipbuilding
facilities in Newport News, Virginia or at Norfolk Naval Shipyard.
Immediately after shipboard testing, the motor shall be subjected to
first article qualification testing as described in the general

Scope. This scope only includes providing a complete and operational
motor and drive system that functions in accordance with this purchase
order and attached general requirements. It includes factory
evaluation software, programming, technical installation and set-up
consultation, system burn-in and debugging. It does not include
follow-on costs for official shipboard testing or first article
qualification testing and reports.

Application description. The VSD and motor shall be driving a 36 inch
diameter warping capstan through a 167.5:1 gear reduction, shall be
able to develop variable line speeds from 0 to 100 fpm in both
clockwise and counter-clockwise directions, shall provide variable
torque output up to 320 lb-ft and shall hold a static torque load of
320 lb-ft indefinitely at stall conditions.

Motor. Provide one motor of a modular class of permanent magnet
brushless (PMB) motors that are designed to drive the warping capstan.
The motors shall be marine grade, high-impact shock and vibration
resistant motors for driven

auxiliaries which are essential to the military effectiveness of a
ship. It includes all associated mechanical and electrical
connecting hardware, mechanical shaft mounted brake, independent
forced air cooling system, and mounting brackets. Reference the
general specification for complete functional and design
requirements of the PMB motor.

Drive. Provide one variable speed drive (VSD) intended for powering
and controlling a permanent magnet brushless DC motor. It shall
include all associated sensors, switching devices, semiconductor
(solid-state) devices, display, diagnostics, and interconnecting
cable required to make a complete system. The power conditioning
system described herein shall be a standardized modular power
conversion and control system for military shipboard applications
suitable for driving PMB motors. The drive shall be
microprocessor-based and provide four quadrant operation of
continuously variable speed and torque control over the entire speed
range of the motor. Controller, rectifier, inverter and other main
VSD components shall be industry standard and interchangeable to the
greatest extent possible. Modules and parts shall be standard
industrial design and interface, versus designed for a unique
application. Vendor shall provide the hardware, software and
technical support necessary to make the PMB and VSD system completely
integrated and operational. VSD shall be mounted in same space
adjacent to the PMB motor below the capstan drive. Reference the
general specification for complete functional and design
requirements of the VSD.

Shipyard support. NNS shall provide system engineering and interface
work required to bring power and control wiring into the VSD cabinet
and cooling support to the motor as necessary [depends on final
cooling method]. All modifications to the existing reduction gear
box, mounting locations or ship foundations required for motor, VSD
or OCS installation shall be performed by NNS.

Technical representatives. Vendor shall provide technical/engineer
support for drive installation, configuration and shipboard
evaluation as needed, to be priced separately. Provide rate quote
for support personnel assistance with system price quote.


Torque-speed characteristic. The variable speed drive shall limit
motor torque output at each speed according to the torque-speed
profile. Motor and VSD for the warping capstan shall be capable of
providing the following minimum torque at the associated speeds in
either forward or reverse direction:

                                 Torque-Speed Profile


  Torque (lb-ft)





                   -100   -80   -60   -40   -20         0   20   40   60   80   100

                                            Line Speed (fpm)


Operator control station (OCS). Provide a portable OCS “boy scout
box” to remotely generate control signals for the VSD and provide
basic feedback information to the operator. The control shall connect
to the existing control station adjacent to capstan head using a
plug-in fitting/adapter and cable. The operator control station is
fundamentally a speed control device as opposed to tension control,
and shall consist of the following operator controls and indicators:

1.   Master lever proportional control. The master lever determines
     the capstan forward and reverse speed control output from 0 to
     100 feet per minute line travel in a 4 to 20 mA analog output
     format. Controller shall limit torque output at each speed
     according to the speed profile. The faster the line speed, the
     less torque is available. Master lever shall be stiffly
     auto-centering at the neutral position. The neutral position
     of the master lever shall not automatically activate the shaft
     brake. The drive system shall automatically sense direction of
     line pull and provide electromagnetic braking action to exactly
     oppose the mooring line force exerted on the capstan.

2.   Shaft brake on/off switch [dual position lever]. The brake
     control shall be a stand-alone manual switch interlocked with
     the master lever. Switch may only be engaged at the neutral
     position of the master lever. When brake is switched on, the
     controller automatically de-energizes the motor no matter what
     torque output is. The shaft brake shall engage when the operator
     activates the brake switch or automatically whenever the motor
     is de-energized.

3.   Alarm indicators. Power failure, thermal overload warning and
     shutdown, […]

4.   Status indicators. Provide high intensity LED indicators for
     self-test, power up, operation at torque limit, and mechanical
     and EM braking modes. Provide separate LED digital readouts for
     motor temperature, line speed, and line tension, […]

Compatibility. The motor shall be designed for use with the existing
167.5:1 reduction gear and mounting bolt pattern used for the
hydraulic drive or electric drive, as applicable. Existing mounting
configuration drawings will be provided…?


Classification summary. The following table is a summary of
performance and arrangement requirements.

Type motor                  Permanent magnet brushless DC
Power supply to VSD         MIL-STD-1399C, 450 VAC, 60 Hz
                            3-phase, ungrounded
Shaft speed                 0 to +/- 2000 rpm
VSD output frequency range 0 to 2 kHz
Maximum torque              320 lb-ft
Shaft extension             Bottom endshield / keyway
Maximum stator winding      150C
Maximum ambient temperature 50C
PMB and VSD duty cycle      Full load continuous
Motor enclosure             NEMA MG 1, IP 55 rating; totally
                            enclosed; frame flange at drive
                            end, blower ventilated
Motor mounting              Vertical, bottom face mounted,
                            drive shaft extension downward,
                            flange mounted, match bolt pattern
                            on existing reduction gear
Electromagnetic braking     125 percent full load continuous
Shaft mounted brake         Navy certified 360 lb-ft minimum
                            torque full load continuous iaw
PMB motor and VSD primary   Air
Coolant circulation         Independent blower, may be shaft,
                            motor, or separately mounted

Mounting flange and adapting hardware. Vendor shall provide
pre-drilled mounting flange and adapting hardware required to secure
the motor, brake and cooling system to the reduction gear. Vendor
shall provide pre-drilled mounting brackets, shock mounts and
adapting hardware required to secure the VSD to the ship.

Shafts. Motor shaft extension for connection to the warping capstan
gear box shall be fitted with a keyway in accordance with … [see

Brake. Provide a Navy qualified secondary mechanical shaft-mounted
brake capable of applying a torque of at least 360 lb-ft without
creepage in accordance with MIL-B-16392C.

Cooling. Provide forced-air cooling of the stator and VSD cabinet
by independent ventilation fan with air filtering and exhaust vent
connections as necessary.


Overload/overcurrent capability. The motor shall be capable of
operating at nominal input voltage at 200 rpm and 1800 rpm for the
minimum operating time at the following overload percentage without
exceeding rated temperature minus 20C:

Torque Rating Overload Table
  Percent Full Load      Minimum Operating Time
         125                   10 minutes
         150                    2 minutes
         200                   20 seconds

Factory testing. Costs for factory testing of complete system shall
be included with PMB motor and drive. Costs for shipboard evaluation
and first article qualification shall be provided separately.


Technical questions can be addressed to:

Stephen J. Smith
Email:    smith_steve@nns.com

Craig Currie
Email:    currie_wc@nns.com

Phone:   (757) 688-1736

         Newport News Shipbuilding, Dept E63
         6060 Jefferson Avenue
         Rouse Tower, Room 4013-B
         Newport News, VA 23605


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