[IGEXMail-0765] NPLB and NPLC interruption

[Jon Clarke <jon.clarke @ npl.co.uk>]

MIME-Version: 1.0
Content-Type: multipart/mixed; boundary="---- =_NextPart_000_01BFC185.7AC364A0"
Reply-To: IGEX Mail <igexmail-owner @ ensg.ign.fr>
Sender: IGEXMail-owner @ ensg.ign.fr
Precedence: list

******************************************************************************
IGEXMail                19-May-2000 12:30:47                   Message No 0765
******************************************************************************

Author: Jon Clarke <jon.clarke @ npl.co.uk> 
Subject: NPLB and NPLC interruption 


------ =_NextPart_000_01BFC185.7AC364A0
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: quoted-printable

Dear Colleagues,=20

during a lightning storm yesterday (about 16:00 UT, 18 May 2000) the =
1pps reference for our Ashtech NPLB and R100 NPLC jumped (to our =
frustration...).=20

It's not clear to us why this should have happened, as all our 1pps and =
5MHz distribution equipment is now on uninterruptible power supplies, =
ruling out a power interruption. There were no lightning strikes nearer =
than several kilometres away, ruling out direct interference. There is a =
200m cable taking a 5MHz between our two buildings, and it lies next to =
other cables. There may have been interference due to this, perhaps a =
large transient on a nearby cable due to a strike on electrical =
equipment elsewhere. To reduce any effects, we have now put an RF =
transformer on the 5MHz supply cable to avoid any ground current flow =
into our distribution equipment.=20

Today (11:00 UT, 19 May 2000) we have reset the reference and equipment. =


Regards,=20
Jon=20

------------------------------------------------------------------------
Mr Jon Clarke                                Time and Frequency Section,
jon.clarke @ npl.co.uk      Centre for Electromagnetic and Time Metrology,
tel: +44 (0) 20 8943 6548                  National Physical Laboratory,
fax: +44 (0) 20 8943 6529        Queens Road, Teddington, TW11 0LW, U.K.
------------------------------------------------------------------------

------ =_NextPart_000_01BFC185.7AC364A0
Content-Type: application/ms-tnef; name="xsmtp-tmp-1.tnef"
Content-Transfer-Encoding: base64
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------ =_NextPart_000_01BFC185.7AC364A0--