b) Partial discharge test ( only for HT Cables)
c) High voltage test
Test Voltages:
The following test voltage is applied between conductor and screen/ armour:
| Voltage
rating of Cables |
Test
Voltage |
| 0.65/1.1 |
kV |
(E) |
3 kV (rms) for 5 minutes |
| 1.9/3.3 |
kV |
(E) |
10
kV (rms) for 5 minutes |
| 3.3/3.3 |
kV |
(UE) |
10
kV (rms) for 5 minutes |
| 3.8/6.6 |
kV |
(E) |
12
kV (rms) for 5 minutes |
| 6.35/11 |
kV |
(E) |
17
kV (rms) for 5 minutes |
| 11/11 |
kV |
(UE) |
28
kV (rms) for 5 minutes |
| 12.7/22 |
kV |
(E) |
32
kV (rms) for 5 minutes |
| 19/33 |
kV |
(E) |
48
kV (rms) for 5 minutes |
In
order to achieve consistency in quality, in addition
to above tests, rigorous quality control measures are
effected at every stage of production. Accordingly,
every batch of raw materials and inprocess cables are
tested to check for their physical and electrical properties.
Differential
Scanning Calorimeter for Thermal Analysis
To
carry out testing and quality control programme, the
manufacturing plant has physical, chemical and electrical
laboratories which are recognised by the Department
of Science & Technology, Government of India. Our R&D
facility is recognised as an in-house R&D unit by the
Department of Science & Industrial Research, Ministry
of Science & Technology, Government of India.
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Besides
standard types, these laboratories also possess special
equipment for precision testing and quality control
particularly for XLPE cable such as Instron Tensile
Testing Machine, Melt Index Tester, Differential Scanning
Calorimeter, Infra-red spectrograph, Oscillating Disc
Rheometer, Microtomes, Blown Film Extruder.
Instron Tensile Testing Machine
Partial Discharge Detection in Finished HT Cables :
This
is a modern PD detection equipment where the discharge
magnitude can be directly read on a calibrated meter.
The detector is associated with 400 kV noise-free transformer,
discharge-free capacitor and suitable matching units.
Besides, specially designed corona free terminators
are used for testing purposes.
Special Features of Partial Discharge Detector Laboratory
500KV
Impulse Generator
The
presence of partial discharge of even minute magnitude
is not desirable in XPLE cables and hence a highly sensitive
detector has been employed with the help of which discharges
as low as 5 pc/cm can be detected. The noise from supply
source is prevented by providing isolating transformer
and low pass filters. The complete equipment is housed
in a specially shielded room to prevent external noise
that would otherwise interfere with the measurements.
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Short
Circuit rating of TROPOTHEN-X cables:
Thermally admissible short circuit current for TROPOTHEN-X cables of 6.6kV to 33 kV grade are depicted in the graph below:
Full load conductor temperature prior to short circuit:
90°C, Maximum short circuit conductor temperature:
250°C
Formula
IK = 0.094 A/ Öt
for Aluminium conductor
and
IK = 0.143 A/ Öt
for Copper conductor
IK
: Short circuit
current in KA (rms)
t
: Duration of
short circuit in seconds
A
: Area of
aluminium conductor in mm2
Short
circuit ratings of cable for one second duration are
given tables below.
For any other duration t seconds divide the value given
in the respective table
by Öt
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Testing
& Quality Control
