CAN ANYONE HELP ME?
CAN ANYONE HELP ME?
(OP)
IS IT POSSIBLE TO USE ARMOUR AS A SHIELD IN CONTROL/PROTECTION CABLES?
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RE: CAN ANYONE HELP ME?
We generally run all instrumentation circuits in metal conduit for added shielding, even though the cable itself is already shielded.
Regards,
dpc
RE: CAN ANYONE HELP ME?
the armor is a double tape aluminium or steel.I wanted to know whether we could earth both ends of armor and save on
buying a more expensive cable .
RE: CAN ANYONE HELP ME?
As far as grounding, for low level signal circuits, grounding is normally done on one end of the shield only, to reduce ground currents.
Regards,
dpc
RE: CAN ANYONE HELP ME?
RE: CAN ANYONE HELP ME?
the GIS manufacturer has said quote"The shielding is recommended although it is not absolutely necessary".
since the project is not a turn key project the manufacturer refuses to provide any information regarding
the level of radiation from GIS switching or the amount
that is transferred from earthing grid to the control
and protection panel.the main contractor offered to use
shielded cable .the cable is a multicore pvc sheathed cable
which has copper screen.I don't know whether this kind of
shield is what that we need.I thought may be the armore
that was already in order could be used instead.also I
read in the standard that a good shielding practice is the
continuity of the shield from GIS to the control panel.
so I thought that maybe we should earth both ends of the
screen.but it seems that I was wrong.
RE: CAN ANYONE HELP ME?
RE: CAN ANYONE HELP ME?
and with the amplitudes of 2 p.u measured at the control
cubicle.I will check the site.
thanks
RE: CAN ANYONE HELP ME?
RE: CAN ANYONE HELP ME?
No ,it's not picovolts
p.u voltage means (actual voltage)/(base voltage) which in the example I told you it means about 2*132KV(for a 132 KV system) at the CVT input for example which is transferred
to the control cubicle through the secondary side of the CVT
the frequency is very high but duration is very short.
and there is no communication problem here only disturbance
to the protection equipment.
RE: CAN ANYONE HELP ME?
RE: CAN ANYONE HELP ME?
the hint that manufacturer gave us.and the current in the
control and protection cables are not high.all of the relays
are numeric with a a very low burden.
RE: CAN ANYONE HELP ME?
going first to a local control cubicle through shielded
and coaxial cables and then they go to the local control and protection panels and we are worried about this route.
by the way there still remains the problem of noise through
ground.
RE: CAN ANYONE HELP ME?