On Systems are leading designers and
manufacturers of COTS power supplies and
complete power conversion equipment for
harsh military environments including Land,
Sea and Air applications.
Focussed entirely on power conversion, our highly experienced team can work with you to ensure that your power conversion requirement is delivered on time and on budget, by utilising a combination of standard COTS modules and semi custom design capabilities.
Our comprehensive range of standard, high quality AC-DC and DC-DC converters, ranging from PCB mounted units of a few watts to large system units of several kW, significantly shorten the development time, ensuring that the most cost effective, reliable, low risk, compliant power converters are selected from the outset of a program.
Fully compliant productOur thorough knowledge of the harsh environments required for Military
COTS power supplies drives our development teams to deliver standard
products that meet the rigours of:
DEF-STAN 61-5 Issue 6, DO-160,
MIL-STD 1275 and MIL-STD 704
surges and transients that protect
your equipment from electrical
damage.
Standard EMC filters and modules
ensure compliance to DEF-STD
59-411 Land Class A, MIL-STD
461 and TEMPEST, our team
can work with you to select the
optimum filter using our in house
pre-compliance EMC test facility.
DEF-STAN 0035, DO 160
and MIL-STD 810 Harsh
environmental specifications
are met with standard product
and are supported for use in
your product with our detailed
application notes.
SURGES AND TRANSIENTS
DEF-STAN 61-5 Issue 6
MIL-STD 1275
MIL-STD 704
EMC AND IMMUNITY
DEF-STAN 59-411 Land Class A
MIL-STD 461
TEMPEST
ENVIRONMENTAL
DEF-STD 0035
MIL-STD 810
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Our in house development team
uses a comprehensive range
of software products to model
your requirement. This up front
design capability ensures that
the optimum design is chosen
very early on in a program to
significantly reduce the design
effort of using standard modules
or providing a complete power
convertor product.
All of our standard Military COTS
products are available as 3D solid
models to reduce your design in
effort backed by industry leading
technical support.
Comprehensive design capabilities
and engineering expertise
Although many applications can
be satisfied using our range of
standard building block modules,
increasingly scarce in house
resource can be freed up by
outsourcing the entire power
supply system.
We offer a highly controlled,
project managed design resource
that can work with you from initial
design concept to final delivery of
a fully compliant power supply or
power system. All of our semi-
custom designs follow our strict
QMS procedures and are supplied
with thorough Design Verification
Testing (DVT) and type test.
Semi-custom design capability
High quality products
Designed and manufactured in the UK to our strict Quality Management
processes of BS EN 9100, ISO14001, IPC-A-610 and J-STD-001 our military
COTS power supplies offer a fully traceable bill of materials with high levels
of workmanship ensuring long service life.
Gated design process
Initial Concept
Specification & Proposal
Product Design & 3D Models
DVT & Prototype
Product Approval
Released to Production
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Thorough in house
test capability
All of our units are subjected to
thorough testing using our in
house test capabilities providing
full parametric operational test
results. This thorough testing
virtually eliminates infant
mortality whilst still maintaining
a cost effective product is
repeatedly delivered.
Urgent Operational
Requirement (UOR)
support
Our UK based design team can
react quickly to support your
UOR requirements by offering a
fast track, immediate response to
your power supply needs. Fast
delivery of standard or modified
stock products, matched by
a dynamic procurement and
supply chain management team
dramatically shortens design-in
and production supply times.
Design with
confidence
All of our Military COTS power
supplies are free from ITAR
restrictions and can therefore be
used with confidence in any UK
military program without the
fear of any future restriction of
supply.
Leading edge R&D and business focus
We consistently invest in R&D to ensure that we provide industry leading
products that offer high efficiency, high power density off the shelf products
that maintain our ethos of COTS power supplies.
Working closely with customers, suppliers and industry champions we
continuously improve the key attributes required to grow our portfolio
of products and our business with strategically important customers and
contracts in the military market.
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Useful Reference Guide to Military SpecificationsThere are two commonly used specifications in the military market; UK MOD DEF-STANs and USA MIL-STDs.
This guide serves to demonstrate some of the key factors that need to be considered when choosing
a power supply for electronic equipment.
Surges and TransientsMost military vehicles are 24V DC systems, commonly referred to as 28V systems. Connected electrical equipment has to meet MIL-STD-1275
and DEF-STAN 61-5 part 6, Avionic equipment has to meet MIL-STD-704.
The figures below show the surges and transients associated with MIL-STD-1275.
Mil 1275 –D surges and Transients for Normal Mode and Generator Mode
0
-250
-300
-200
-150
-100
-50
0
50
100
150
200
250
300
100 200 300 400 500 600 700 800 900 1000
RECOVERY TIME (mS)
Envelope of Spikes in Normal Operating Mode for 28 VDC Systems
VO
LTS
250V, 70µs
-250V, 70µs
40V, 1mS
25V TO 30V
-40V, 1mS
STEADY STATE VOLTAGE
0
-250
-300
-200
-150
-100
-50
0
50
100
150
200
250
300
100 200 300 400 500 600 700 800 900 1000
RECOVERY TIME (mS)
Envelope of Spikes in Generator-only Mode for 28 VDC Systems
VO
LTS
250V, 70µs
-250V, 70µs
100V, 1mS
23V TO 33V
-100V, 1mS
STEADY STATE VOLTAGE
DEF-STAN 61-5 part 6 issue 6This standard covers both 12V and 24V vehicle systems. It differentiates between the voltages seen in the vehicle original fit equipment,
(Platform) and those seen by any externally connected equipment (Terminal).
On Systems power supplies are designed to meet the harsher Platform equipment levels as standard.
PLATFORM AND TERMINAL EQUIPMENT OPERATING VOLTAGES
NOMINAL 12V NOMINAL 24V
TERMINAL EQUIPMENT
PLATFORM EQUIPMENT
TERMINAL EQUIPMENT
PLATFORM EQUIPMENT
LOWER VOLTAGE 9V 9V 18V 18V
UPPER VOLTAGE 16V 19V 32V 38V
0
5
0
10
15
20
25
30
35
40
45
100 200 300 400 500 600 700 800 900 1000
RECOVERY TIME (mS)
Envelope of Surges in Normal Operating Mode for 28 VDC Systems
VO
LTS
40V, 50mS
18V, 500mS
32V, 500mS
23V, 600mS
STEADY STATE VOLTAGE LIMITS
32V30V
23V25V
18V
0
10
0
20
30
40
50
60
70
80
90
100
110
100 200 300 400 500 600 700 800 900 1000
RECOVERY TIME (mS)
Envelope of Surges in Generator-only Mode for 28 VDC Systems
VO
LTS
100V, 50mS
STEADY STATE VOLTAGE LIMITS
40V
33V
16V23V
15V
40V, 500mS
16V, 600mS15V, 500mS
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Short Transients
SurgesThe figures below show the harsher surges and long transients for terminal equipment in 12V and 24V vehicles.
0.001
0
5
10
15
20
25
0.1 ∞1.00.01
RECOVERY TIME (SECONDS)
DETA03.A – 12V LIMITS
PEA
K V
OLT
AG
E (V
OLT
S)
20V, 0.05s
16V, 0.1s
11.5V, 0.5s
15V, 1.0s
12.5V, 1.0s
STEADY STATE >1s
DETA03.A – 24V LIMITS
0.001
0
10
20
30
40
50
0.1 ∞1.00.01
RECOVERY TIME (SECONDS)
PEA
K V
OLT
AG
E (V
OLT
S)
40V, 0.05s
32V, 0.1s
25V, 0.5s
30V, 1.0s
25V, 1.0s
STEADY STATE >1s
12VSYSTEM VOLTAGE 24V
Pulse amplitude -150V -200V
Positive pulse
Durations: t1 = 100µS t2=10mS t3=90mS Impedance = 50Ω
100V 200V
These transients simulate the spike present from relay switch arcing and other electro mechanical switch bounce. The unit must withstand
both positive and negative short transients, positive transients are identical in shape to those shown above.
NEGATIVE PULSE TRANSIENTS
0
Vs
VA
t3t2
t1
V
Load DumpA very harsh surge is the load dump. This is present in vehicle systems that have a loose battery connection.
This is classed as an extreme condition and equipment is allowed to turn off during the surge. On Systems have products that can operate
through this surge without turning off. This is particularly useful in systems that have a long re-boot time.
0
50
0
100
150
200
250
50 100 150 200 250 300 350 400
TIME (ms)
Parameter 12V 61-5 System 24V 61-5 System 24V 1275 System
Vpk 111V 202V 100V
Rise time 10ms 10mS 0mS
Period 0mS 0mS 50mS
Decay time 400ms 350mS 10mS
Energy 4j/Amp 30J/Amp 3J/Amp
Source impedance 0.5 Ohms 1 Ohm 0.5 Ohms
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MIL-STD-704, 28V DC equipment which is required to operate in emergency conditions, must do so with an extended DC steady state range
between 16 and 29 volts. This does not apply to 270V DC equipment.
DO 160 classifies equipment into four categories, A B Z and D, the result is a more complex document that cannot be captured in this
reference guide. The electrical specification is similar to MIL-STD-704, and common requirements include 50mS holdup for category B
equipment and 200mS for category Z. This large holdup time can challenge the design of the power supply, On Systems have products
that conform to both requirements in a compact footprint.
0.00040
60
80
100
120
140
160
180
200
TIME FROM ONSET OF TRANSIENT (SECONDS)
Envelope of Normal AC Voltage Transients
VO
LTS,
DC 118V, 0.0875s
0.025 0.050 0.075 0.100 0.025 0.125 0.150 0.175
108V, 0.080s
80V, 0.010s
180V, 0.010s
118V
108V
113V
0.00010
20
30
40
50
60
TIME FROM ONSET OF TRANSIENT (SECONDS)
Envelope of Normal Voltage Transients for 28 Volts DC Systems
VO
LTS,
DC
29V, 0.0825s
0.025 0.050 0.075 0.100 0.025 0.125 0.150 0.175
22V, 0.1000s18V, 0.0150s
50V, 0.0125s
0180
200
220
240
260
280
300
320
340
TIME FROM ONSET OF TRANSIENT (SECONDS)
Envelope of Normal AC Voltage Transients for 270 Volts DC Systems
VO
LTS,
DC
0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.1
250V, 0.040s
200V, 0.010s
330V, 0.020s
280V
250V
280V, 0.040s
MIL STD 704F & DO 160F – Avionic systems
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EMC and SusceptibilityThe USA standard MIL-STD-461 and UK standard DEF-STAN-59-411 (replaced DEF-STAN-59-41) are used to limit the amount of electrical
noise introduced onto the electrical system, and ensure that electrically coupled noise on the system doesn’t affect the equipment.
EMC emissions are the most difficult to achieve compliance to and the levels are shown in the figures below.
MIL-STD-461F – Limits for all systems including the relaxation levels for different input voltages.
DEF-STAN-59-411 – Limits for Land Service Use for different classes of equipment.
Environmental SpecificationsUSA Specification MIL-STD-810 land air and sea and UK Specification DEF-STAN-0035, define the limits and severity levels that the equipment
will be subjected to. The levels of shock, vibration, temperature, water ingress, atmospheric pollution and humidity vary considerably
depending on where the equipment is installed.
It is vital that these environmental requirements are considered when designing in a power supply to ensure a long equipment lifetime.
Thermal management along with mechanical integration have the largest impact on reliability, On Systems engineers have considerable
knowledge of selecting and designing in a power supply to ensure that you use a reliable, cost effective product in your equipment.
10Hz0
20
40
60
80
100
120
140
FREQUENCY
CO
ND
UC
TED
EM
ISSI
ON
CU
RR
ENT
dBµA
100Hz 1kHz 10kHz 100kHz 1MHz 10MHz 100MHz 1GHz
Class D
Class C
Class B
Class A
150MHz, 40dB
4kHz, 130dB
300kHz, 40dB
500Hz, 130dB
150MHz,25dB600kHz,25dB
150MHz, 10dB1.2MHz, 10dB
150MHz, 0dB2MHz, 0dB
NOMINAL EUT SOURCE VOLTAGE (AC & DC) LIMIT RELAXATION
28V BASIC CURVE
115V
220V
270V
=/> 440V
6dB
9dB
10dB
12dB
10k40
50
60
70
80
90
100
110
FREQUENCY (Hz)
LIM
IT L
EVEL
(dB
µV
)
100k 1M 10M 100M
BASIC CURVE
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This useful reference guide is intended to demonstrate the requirements of Military power supplies, it is not intended for use as a design document and On Systems recommends that
original copies of the specifications must be used for equipment design. On Systems cannot accept responsibility if this document is used outside it’s intended purpose.