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| Surge Arrester Specification |
Surge Arrester Requirements for 132kV and 33kV Underground Cable Line Projects
Surge arresters shall be of
the type employing non-linear metal oxide resistors without spark gaps. The
Contractor shall demonstrate by calculations that the surge arresters will
adequately protect the switchgear arrangement proposed.
Arresters shall be designed
and tested in accordance with the requirements of IEC 99 4. Any departure shall
be the subject of agreement between the Engineer and the Contractor. Routine
tests shall be carried out in accordance with the requirements of Section 15 of
this Specification.
Surge arresters shall be
housed in porcelain insulators designed to withstand extremes of the
environment described. The insulation shall have a minimum creepage distance of
25 mm/kV rated system phase-to-phase voltage. Porcelain shall comply with IEC
233. The method of sealing against the ingress of moisture shall be of a type
well proven in service and the manufacturing procedures shall include a practical leak test which can be demonstrated to the inspecting engineer if
required.
The internal components of
arresters shall be arranged to minimize radial voltage stresses, and internal
corona and to ensure minimal capacitive coupling with any conducting layer of
pollutant on the outside of the porcelain housing except where approved,
organic materials are not permitted.
Good electrical contact shall
be maintained between resistor blocks, considering any thermal expansion
and contraction of the block or mechanical shock during transport and erection,
by installing a well-proven clamping system.
Metal oxide arresters
installed outdoors shall be able to dissipate when new, twice the energy
generated in the resistor blocks when energized at their maximum continuous
operating voltage immediately having been subjected to the discharge duties
specified in IEC 99 4 and assuming that the porcelain housing and the
surrounding air is at least 5˚C higher than the maximum ambient air temperature
specified.
Good quality control of the
manufacturing process of the resistors shall be ensured by rigorous testing
procedures. The procedures shall ensure that the characteristics of the blocks
are, and will remain, within the specified limits when new and throughout the
anticipated life of the arresters. Samples may be selected at random by the
Engineer for special tests to be agreed upon with the manufacturer.
All surge arresters shall be
fitted with a pressure relief diaphragm which shall prevent explosive
shattering of the porcelain housing in the event of an arrester failure and the
arrester shall have been tested according to the high and low current tests
specified in IEC 99 1.
Arresters shall be supplied
completely for installation in an outdoor switchyard, including supporting
structures, insulating bases, and surge counters, one per phase, and, if
applicable, grading rings. The material used for terminals shall be compatible
with that of the conductors to which they are to be connected.
Each arrester shall be
identified by a rating plate in accordance with the requirements of IEC 99 4.
In addition, an identification mark shall be permanently inscribed on each
separately housed unit of a multi-unit arrester so that units can be replaced
in the correct position in the event of them being dismantled.
Surge counters shall have an
internal assembly that is matched to the line discharge capability of the
arrester and shall include a leakage current meter with a bilinear scale for
ease of reading. Auxiliary contacts are to be provided to signal remote
indications of the counter operation.
Sponsored:
Technical Data Schedule for 132 kV and 33 Surge Arrester
Sl. No.
|
Item no.
|
Unit
|
Nominal System Voltage
| |
132 kV
|
33 kV
| |||
1.
|
Manufacturer
| |||
2.
|
Model Number
| |||
3.
|
Type:
| |||
4.
|
Continuous operating voltage
|
kV RMS
| ||
5.
|
Rated voltage
|
kV RMS
| ||
6.
|
Standard nominal discharge current
|
kV
| ||
7.
|
Reference current at ambient temperature
|
mA
| ||
8.
|
Reference voltage for above
|
kV RMS
| ||
9.
|
Steep current impulse residual voltage
|
kV pk
| ||
10.
|
Lightning impulse residual voltage at
| |||
5 kA
|
kV pk
| |||
10 kA
|
kV pk
| |||
20 kA
|
kV pk
| |||
11.
|
Duty Class
| |||
12.
|
Discharge Class
| |||
13.
|
Pressure relief class
| |||
14.
|
Nominal Diameter of resistor blocks
|
mm
| ||
15.
|
Number of resistor blocks connected electrically in parallel
| |||
16.
|
Number of separately housed units pre-phase
| |||
17.
|
Overall height of arrester (without supporting structure)
|
m
| ||
18.
|
Overall height of arrester including grading ring if applicable
|
mm
| ||
19.
|
Clearances:
| |||
Phase to earth (from center line)
|
mm
| |||
Phase to phase (center line to center line)
|
mm
| |||
20.
|
Overall height of arrester (without supporting structure)
|
kg
| ||
21.
|
Maximum cantilever strength
|
Nm
| ||
22.
|
Maximum force due to the wind (at maximum specified gust speed)
|
Nm
| ||
23.
|
Minimum creepage distance over the insulator
|
mm
| ||
