‘Hi Pot Test’, ‘Flash Tested’, ‘Withstand Voltage’, ‘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 component designed to provide electrical isolation, to verify the integrity of that isolation.
Murata Power Solutions NMPD01 series of power over ethernet modules are all 100% production tested at their stated isolation voltage. This is 1500VAC for 60 seconds.
A question commonly asked is, “What is the continuous voltage that can be applied across the part in normal operation?”
The NMPD01 series has an on-board DC/DC converter, that has been recognized by Underwriters Laboratory. 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 barrier; 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 according 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 materi-
als, construction and environment. While manufactured parts can withstand several times the stated test voltage, the isolation capability does depend on the wire insulation. Any
material, including this enamel (typically polyurethane) is susceptible 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 testing, but if it is absolutely required, that the voltage be reduced by 20% from
specified test voltage.
APPLICATION NOTES
The NMPD01 series are ideal modular system blocks for integration into numerous ethernet products to be powered from the data lines. These modules eliminate the need for
localised powering saving considerable installation costs and time. These modules are ideal for applications where powering from the PSE at an SELV level is highly desirable such
as in harsh industrial environments (chemicals and moisture).
Offering a module solution, incorporating ethernet isolation transformers, full compatibility signature to the PSE and isolated on-board DC/DC converter the NMPD01 series offers
simple and quicker product development, maximising return on investment. PoE is the emerging standard in what is in effect the widest form of distributed power architecture.
Power-Up Sequence
A PSE applies two separate input voltages of <10V and calculates the signature resistance and signature capacitance of the POE device. If it is in the valid range, the PSE
then applies a voltage between 14.5V and 20.5V and measures the classification current. If the classification current is between 0-4mA it is classification O.
PSE applies full operating voltage 42-57V, detection circuitry within NMPD01 senses correct voltage and turns on on-board DC/DC converter. If input voltage falls outside
specified operating range, the on-board DC/DC converter is disabled.
Maximum Power
If the maximum output power is exceeded, the NMPD01 will operate in over current mode and will auto recover when the over load condition is removed.
Application Sectors
Security system, door access, cameras, alarms
Displays
Public address systems
Wireless access point
Environmental control
Telemetry
Remote environmental monitoring
RoHS COMPLIANCE INFORMATION
This series is compatible with RoHS soldering systems with a peak wave solder temperature of
300ºC for 10 seconds. The pin termination finish is Tin. They are backward compatible with Sn/Pb
soldering systems.
For further information, please visit www.murata-ps.com/rohs
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