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38
Z X 1 . 5 - R
6.4.5 Maintenance earthing
•
Earthing of the busbar with the bus tie/riser,
as described in section 3.10
•
Earthing with an earthing and short-circuiting set
Handling during earthing with an earthing and
short-circuiting set:
(Figures 6/1 and 6/7)
The plugs shown in figure 6/7 in conjunction with
corresponding short-circuiting and earthing cable
sets are to be used for maintenance earthing.
The short-circuit withstand capability of the
cable set must correspond to the conditions of the
switch-gear installation.
Caution!
Observe the notes in Section 3.8 on the interlock
dependencies for all work with earthing and
short-circuiting sets!
•
Isolate the switchgear area in accordance with
the safety rules of VDE 0105 and secure it to
prevent reconnection
•
Unscrew surge arresters where fitted and
close off the exposed sockets with insulating
cable dummy plugs
•
Close off empty cable sockets with insulating
cable dummy plugs
•
Check the test plugs to ensure that the surface
is clean and dry, and clean them if necessary
•
Carefully screw the short-circuiting and earthing
cable set to the test plug
•
Connect the common earthing connector of the
cable set to the earthing terminal of the panel
•
Unscrew cable dummy plugs (1.5) in the relevant
test socket (1.4) and remove it
•
Insert the test plugs into the prepared test
sockets and screw them tight
6.5 Safety note on operation of the voltage
transformers
The screws marked in figure 5/13 establish the
earthing connections to the relevant cable
terminals in the terminal box shown (illustration
shows condition as delivered).
I N S T R U C T I O N M A N U E L
•
Verify the off-circuit condition with a
suitable (hand- held) display unit at
measuring sockets (1.6) or (4.5) on the
capacitive voltage indicator system
The wiring and in particular the earthing of the
secondary terminals is to be implemented in
accordance with the circuit diagrams!
Releasing the earthing screw on the "N"
terminal leads to potentially lethal high
voltage at the terminal during operation
of the voltage transformers!
Releasing earthing screw "N" is only
permissible when the voltage transformers
are off-circuit on the primary side (for test
purposes)!
The relevant switchgear section is to be isolated
and earthed before the isolating system for the
voltage transformers is operated! (The 5 VDE
safety rules are to be observed.)
Always use original earthing screws!
6.6 Application of the X-ray regulations
One of the physical properties of vacuum
insulation is the possibility of X-ray emissions
when the contact gap is open. The specified type
test performed by the Physikalisch-Technische
Bundesanstalt (PTB) in Brunswick in Germany
demonstrates that the local dosage output of 1
μSv/h at a distance of 10 cm from the touchable
surface is not exceeded.
The results are as follows:
•
The use of the vacuum interrupters at rated
voltage is completely safe
•
Application of the rated power frequency
withstand voltage specified for the switching
device by VDE 0670 and IEC 62271 or a DC voltage
of 48 kV or 70 kV during cable tests is also safe
•
Higher voltages than the rated power frequency
withstand voltage specified in DIN VDE or IEC
standards or the DC voltage must not be
applied
•
Fulfillment of the above requirement with the
vacuum interrupter in the open position is
dependent on maintenance of the specified
distance between the contacts (which is
automatically ensured with correct mechanism
function and force transmis sion)
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