[TCUG] Re: 6 year electrical testing
- From: Keith Brunt <keithbrunt@xxxxxxxxxxxxxxxxxxxxxxx>
- To: "'tcug@xxxxxxxxxxxxx'" <tcug@xxxxxxxxxxxxx>
- Date: Tue, 15 Jun 2004 15:43:06 +0100
The phase drive cards use either a fuse 5mm Dia x 20mm -BS4265 or the
slightly larger ones 6.3mm Dai x 32mm - BS2950 both are intended for use in
the electronic/telecom market where back is afforded by a 13a plug top fuse
not a whopping great big 32amp thing!
It beats me why controllers are not designed with all BS88 fuses. They are a
quality fuse very accurate.
Keith Brunt
-----Original Message-----
From: Bill Emett [mailto:bill.emett@xxxxxxxxxxxxxxxxxxxxxxx]
Sent: 15 June 2004 15:34
To: tcug@xxxxxxxxxxxxx
Subject: [TCUG] Re: 6 year electrical testing
Although it can be calculated it still must tested to prove compliance
with BS5750.
Thanks for the info on types of fuses in phase drive cards,I was given
the impression by a contractor that they were to BS 88 seems not.
>>> Paul.Welsh@xxxxxxxxxxxxxxxxxx 15-Jun-04 3:19:31 pm >>>
It is the impedance that matters. It must be low enough to ensure that
the
fuze blows as specified. With the live feed impedance and drive
impedance
known, this can be readily calculated. Dave Thompson did a piece on
this a
couple of years back.
Noting the "test every pedestal" comment, rember the pedestal isn't
enough
every remote point on every pedestal. Once set up at a pedestal, it
doesn't
take long, open each head, test, record, open the push button, test,
record,
test the pedestal earth bond and record. The worst part is walking
around
with the ladder and removing the pole cap.
PW
-----Original Message-----
From: Bill Emett [mailto:bill.emett@xxxxxxxxxxxxxxxxxxxxxxx]
Sent: 15 June 2004 15:12
To: tcug@xxxxxxxxxxxxx
Subject: [TCUG] Re: 6 year electrical testing
I also agree with a test on all poles, also that damage could occure
to
the lamp drives during testing, but as the lamp drives form part of
the
path to the pole then they would have to be included in any ELI
results
to prove a low enough impedance to isolate the pole within 5s of a
live
short to the pole.
>>> Paul.Welsh@xxxxxxxxxxxxxxxxxx 15-Jun-04 2:54:06 pm >>>
The acceptable impedance has to take account of the actual circuit.
The
fuse used for the test needs to have a reasonable value to ensure that
it
withstands the test current. Which is why testing through the lamp
drives
should be avoided, it could damage them. There are claims that they
should
not be damaged, but why take a risk of abusing a device not designed
for the
test load?
As for 20% testing, don't risk it! Remember there have been knock
downs
etc
in the preceding six years, this isn't a nice cosy house, it is a much
harsher environment. The site file should have copied of impedance
tests
from each repair, but are they being done/recorded? (If not why not?)
The
six year test updates the whole site record and needs to be completed
and
filed.
PW
-----Original Message-----
From: Bill Emett [mailto:bill.emett@xxxxxxxxxxxxxxxxxxxxxxx]
Sent: 15 June 2004 14:44
To: tcug@xxxxxxxxxxxxx
Subject: [TCUG] Re: 6 year electrical testing
Why would you need to disconnect all cores at pole top, surely only
one
core would be necessary to form a circuit to test and an ELI test will
also prove armoring.
Most courses on this subject relate to house wiring which suggests you
only have to test 20% of the system this should reduce the down time
if
applied to signals. Unless this 20% shows a problem then the whole
system has to be checked.
One of the queries I have is with E.L.I testing at poles is as
follows,
Our contractors tell me they use a spare live feed but this would only
test straight from the origin via whatever fuse they use to the pole
back via the armored cable and the usual Manweb path to the substation
this is bound to give a favourable result.
This can't give the practical reading via the phase drive circuits
which are essentially in series and have there own resistance which
must
be included in the E.L.I figure.
A figure quoted for a max E.L.I test for a particular controller is 5
ohms which is down to the 10A fuse on the phase drive card, not the
main
20 or 30 amp fuse in the supply which this figure would fail.
>>> chris.gladwyn@xxxxxxxxxxxxxxxxxx 15-Jun-04 1:33:39 pm >>>
************************************************************************
This email contains confidential information, solely for the
person/organisation intended. If you received it in error,
please contact the sender right away and do not copy this email for
any
purpose, or disclose its contents to any person. The contents of an
attachment to this email may contain software viruses which could
damage your own computer system. While Owen Williams has taken every
reasonable precaution to minimise the risk, we cannot accept liability
for any damage which you sustain as a result of software viruses. You
should carry out your own virus checks before opening the attachment.
************************************************************************
-----------------------------------------------------------
A message from the TCUG mailing list. For information about
the list visit //www.freelists.org/webpage/tcug
-----------------------------------------------------------
A message from the TCUG mailing list. For information about
the list visit //www.freelists.org/webpage/tcug
************************************************************************
This email contains confidential information, solely for the
person/organisation intended. If you received it in error,
please contact the sender right away and do not copy this email for
any
purpose, or disclose its contents to any person. The contents of an
attachment to this email may contain software viruses which could
damage your own computer system. While Owen Williams has taken every
reasonable precaution to minimise the risk, we cannot accept liability
for any damage which you sustain as a result of software viruses. You
should carry out your own virus checks before opening the attachment.
************************************************************************
-----------------------------------------------------------
A message from the TCUG mailing list. For information about
the list visit //www.freelists.org/webpage/tcug
-----------------------------------------------------------
A message from the TCUG mailing list. For information about
the list visit //www.freelists.org/webpage/tcug
*************************************************************************
The contents of the e-mail and any transmitted files are confidential and
intended solely for the use of the individual or entity to whom they are
addressed. Transport for London Street Management hereby excludes any
warranty and any liability as to the quality or accuracy of the contents of
this e-mail and any attached transmitted files. If you are not the intended
recipient, be advised that you have received this e-mail in error and that
any use, dissemination, forwarding, printing or copying of this e-mail is
strictly prohibited.
If you have received this e-mail in error please notify
postmaster@xxxxxxxxxxxxxxxxxxxxxxxx
This footnote also confirms that this email message has been swept for the
presence of computer viruses.
*************************************************************************
-----------------------------------------------------------
A message from the TCUG mailing list. For information about
the list visit //www.freelists.org/webpage/tcug
Other related posts:
