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NAVSO
P-3641: Navy Power Supply Reliability Design & Mfg
Guidelines

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3.2 Development Schedule and Cost

CUSTOM POWER SUPPLY DEVELOPMENT
SCHEDULES

Power supplies may be developed by the system
manufacturer or subcontracted to a power
supply specialist. System and power supply
manufacturers agree that a typical development
schedule is 18 months, as shown in Figure 3-1.
This schedule assumes that the power supply
circuits are similar to past designs,
reconfigured and qualified to the specific new
requirements.

When a state-of-the-art power supply is
required, time to develop and qualify the power
supply is typically 24 months. Such
state-of-the-art designs often include use of
custom integrated or hybrid microcircuits, use
of multi-layer interconnect or metal core
boards, switching frequencies over 100 kHz and
other techniques aimed at reliably increasing
the power output density.

The development and qualification time for a
custom power supply design can be reduced if the
required circuits have been previously packaged
in building blocks or modules that will require
minimal layout and design modification. The
schedule then may be limited primarily by
critical military power supply component
procurement lead times, which often approach 12
months.

COST OF A CUSTOM POWER SUPPLY IN
MAN-HOURS

Manpower loading for the development of a
typical power supply is given in Figure 3-1
and in Table 3-1.

TABLE
3-1. TYPICAL REQUIRED LABOR FOR THE
DEVELOPMENT

OF A CUSTOM POWER SUPPLY

HOURS

HOURS

Electronics
Engineer

1,200

Manufacturing
Engineer

400

Engineering
Technician

600

Drafting (full
documentation)

1,200

Mechanical
Engineer

450

Assembly

300

Desginer

600

Quality
Assurance Inspection

100

Reliability
Engineer

200

Qualification
Testing

500

Components
Engineer

300

Special Test
Equipment

200

Stabability
Analyst

50

Project
Engineer

400

Thermal
Analyst

100

Material costs must be
added to the man-hour

costs

--------

TOTAL
HOURS:

6,600

Note:
Additional man-hours will be required on
high-voltage designs.

COST AS A PERCENTAGE OF SYSTEM COST

System contractors who both manufacture and
purchase their power supplies estimate the
power supply development cost at 5% to 10% of
the total electronic system development cost,
excluding software. The development cost is
estimated on the basis of anticipated man-hours
plus material, which often includes
subcontracted environmental and electromagnetic
interference (EMI) testing. The development cost
must be modified upward for a state-of-the-art
design. Recurring power supply cost may be
estimated as 2.5 to 5 times the bill of material
plus additional costs imposed as a result of
production environmental testing, components
screening and specialized procedures. This
typically results in 5% to 10% of the total
recurring system production cost.

CONCLUSION

The reality of power supply development
schedule and cost is often in direct conflict
with a prime contractor's expectations less
than six months, with a nonrecurring effort of
less than 1,000 man-hours. The Navy requires
that power supply problems be clearly recognized
and priorities for power supplies be upgraded
with the appropriate assignment of
resources.