786 Series
General Purpose Pulse Transformers
TUBE OUTLINE DIMENSIONS
10.95
(0.43)
4.00 (0.16)
0.60±0.15
(0.023±0.005)
12.95
(0.51)
TECHNICAL NOTES
ISOLATION
VOLTAGE
‘Hi Pot Test’, ‘Flash Tested’, ‘Withstand Volt-
age’, ‘Proof Voltage’, ‘Dielectric Withstand
Voltage’ & ‘Isolation Test Voltage’ are all terms
that relate to the same thing, a test voltage,
applied for a specified time, across a compo-
nent designed to provide electrical isolation, to
verify the integrity of that isolation.
All products in this series are 100% production
tested at their stated isolation voltage.
A question commonly asked is, “What is the
continuous voltage that can be applied across
the part in normal operation?”
For a part holding no specific agency approv-
als both input and output should normally be
maintained within SELV limits i.e. less than
42.4V peak, or 60VDC. The isolation test
voltage represents a measure of immunity to
transient voltages and the part should never
be used as an element of a safety isolation
system. The part could be expected to function
correctly with several hundred volts offset
applied continuously across the isolation bar-
rier; but then the circuitry on both sides of the
barrier must be regarded as operating at an
unsafe voltage and further isolation/insulation
systems must form a barrier between these
circuits and any user-accessible circuitry ac-
cording to safety standard requirements.
REPEATED HIGH-VOLTAGE
ISOLATION TESTING
It is well known that repeated high-voltage
isolation testing of a barrier component can
actually degrade isolation capability, to a
lesser or greater degree depending on ma-
terials, construction and environment. This
series has toroidal isolation transformers,
with no additional insulation between pri-
mary and secondary windings of enameled
wire. While parts can be expected to with-
stand several times the stated test voltage,
the isolation capability does depend on the
wire insulation. Any material, including this
enamel (typically polyurethane) is suscep-
tible to eventual chemical degradation when
subject to very high applied voltages thus
implying that the number of tests should be
strictly limited. We therefore strongly advise
against repeated high voltage isolation test-
ing, but if it is absolutely required, that the
voltage be reduced by 20% from specified
test voltage.
This consideration equally applies to agency
recognized parts rated for better than
functional isolation where the wire enamel
insulation is always supplemented by a
further insulation system of physical spacing
or barriers.
5.50 (0.22)
3.80
(0.15)
15.70 (0.62)
Tube length: 465±2 (18.3±0.08). Tube quantity: 50.
Tube material: Antistatic coated clear pvc.
Unless otherwise stated all dimensions in mm (inches) ±0.25 (0.01).
USA:
UK:
France:
Japan:
Mansfield (MA), Tel: (800) 233 2765, email: sales@murata-ps.com
Milton Keynes, Tel: +44 (0)1908 615232, email: mk@murata-ps.com
Montigny Le Bretonneux, Tel: +33 (0)1 34 60 01 01, email: france@murata-ps.com
Tokyo, Tel: 3-3779-1031, email: sales_tokyo@murata-ps.com
Osaka, Tel: 6-6354-2025, email: sales_osaka@murata-ps.com
Website: www.murata-ps.jp
Shanghai, Tel: +86 215 027 3678, email: shanghai@murata-ps.com
Guangzhou, Tel: +86 208 221 8066, email: guangzhou@murata-ps.com
Canada:
Toronto, Tel: (866) 740 1232, email: toronto@murata-ps.com
Murata Power Solutions, Inc.
11 Cabot Boulevard, Mansfield, MA 02048-1151 U.S.A.
Tel: (508) 339-3000 (800) 233-2765 Fax: (508) 339-6356
www.murata-ps.com email: sales@murata-ps.com
ISO 9001 REGISTERED
Murata Power Solutions, Inc. makes no representation that the use of its products in the circuits described herein, or the use of other
technical information contained herein, will not infringe upon existing or future patent rights. The descriptions contained herein do not imply
the granting of licenses to make, use, or sell equipment constructed in accordance therewith. Specifications are subject to change without
notice.
© 2008 Murata Power Solutions, Inc.
Germany:
München, Tel: +49 (0)89-544334-0, email: ped.munich@murata-ps.com
China:
www.murata-ps.com
Technical enquiries - email:
mk@murata-ps.com,
tel:
+44 (0)1908 615232
KMP_786C_B02
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