Hi Charlie:
If the ship can be connected to shore power, then the ship may be subject to
"normal" (shore-based) transient voltages, in which case your equipment must
meet the clearances for 2,000 volts peak. However, the specified at-sea
ship-board 1,000 volts peak is reasonable since lightning strikes on
overhead wires is unlikely.
According to Table 10, the clearance dimension for 1,000 volts peak is 0.26
mm (0.8 mm for pollution degree 3), and for 2,000 volts peak is 1.2 mm.
These are very small distances. Chances are the equipment has clearances
greater than 1.2 mm, so it meets both 1,000 and 2,000 volts peak criteria.
(Dimensions of a fraction of a millimeter require special control.)
If you are planning on third-party certification to 62368-1, I would expect
that the certification house would insist on 2,000 volts peak and the 1.2 mm
clearance despite ship-board 1,000-volt transient voltage.
Stay safe, and best regards,
Rich
From: Charlie Blackham <[email protected]>
Sent: Wednesday, March 3, 2021 8:23 AM
To: [email protected]
Subject: [PSES] Determination of Maximum transient voltage on naval ships
All
I'm currently doing a LVD safety assessment for a rack of Radio
Communication equipment going onto naval ships and using EN 62368-1
The equipment is powered at 115 60 Hz
Clearance distances are based on maximum transient voltages which for normal
(shore based) installations is given as 2000 V for 115 V installations per
EN 62368-1 clause 5.4.2.2 referencing 5.3.3.2.3 of IEC 60664-1:2007
The 115V AC system on a ship is not subject to the same over voltage
transients as land based equipment
Google has found US publication S9086-KY-STM-010/CH-320R2
<https://fas.org/man/dod-101/sys/ship/nstm/ch320.pdf> , Naval Ships'
Technical Manual Chapter 320 Electric Power Distribution Systems
Maximum voltage transient of 1000 V on 115 V systems - this is also in
MIL-STD-1399-300-1
<http://everyspec.com/MIL-STD/MIL-STD-1300-1399/MIL-STD-1399-SECT-300_PART-1
_55833/> TABLE II. Characteristics of shipboard electric power systems
I'm basically trying to determine the minimum Clearance requirements to be
applied so that the client can CE mark the system - is it reasonable to use
this 1000V for determining required clearance in Table 11?
Or, any reason why it's not reasonable ?
Thank you in advance for your thoughts
Best regards
Charlie
Charlie Blackham
Sulis Consultants Ltd
Mead House
Longwater Road
Eversley
RG27 0NW
UK
Tel: +44 (0)7946 624317
Email: <mailto:[email protected]> [email protected]
Web: <https://sulisconsultants.com/> https://sulisconsultants.com/
Registered in England and Wales, number 05466247
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