定位测试仪

LECOM 英国工厂生产：
最新电缆及开关柜：局放测试仪、检测仪器。
我们的专长：在强电场干扰环境可以正常使用。
Expertise in determining Partial Discharge (PD) signals in noisy electrical environments

What is Partial Discharge? 什么是局放
‘Electrical discharge that does not completely bridge the space between two conducting electrodes’
Where in insulation does PD occur? 局放产生的位置

What are the effects of PD? 局放会带来什么危害
Individual discharges are low energy but they are very localised and can be very repetitive.
Damage is caused by;
Mechanical – Ionic bombardment
Thermal – Local heating at discharge site
Chemical – Discharge energy breaks chemical bonds

Classification of PD 局放的等级
Switchgear PD can be classified into 3 distinct types
Corona – Ionization of fluid (air) surrounding conductor – usually visible.
(Surface) Tracking – Electrical tracking over contaminated insulator
Arcing – Electrical breakdown of a gas that produces plasma discharge

PD and Noise 局放与背景噪声
Every substation or test point has background noise in the frequency range of TEV devices.
The majority of background noise is within acceptable ranges and will not interfere with TEV signals.
However, some noise will be high enough to interfere with correct measurement of PD activity
Common causes of background noise:

Fluorescent lighting inside substations
Can generate high noise signals very local to measurement point
Simple to remove
Induced EMC noise from local equipment, e.g. Transformers
Difficult to remove
Usually lower level
Air Conditioning or environmental controls
Easy to remove
Differentiating between PD and Noise is the KEY to effective PD detection. The LECOM PD-LSGS has an in-built noise rejection method;
Pulses per cycle:
The LECOM PD-LSGS has a built in Noise rejection system. Informing the user when detected pulses are too frequent in the power cycle to be PD.
When the LECOM PD-LSGS detects noise, the screen will
Alternate between a Noise warning and the dB
Reading detected.

The test systems will identify noisy environments.
Confirm this by placing the device within the substation but away from the switchgear:
      – On cabinets
      – Metal panels
      – etc
It is important to then attempt to remove the noise:
      – Check the common sources

Most noise will fall within acceptable limits (that is < 30dB)
Noise higher than 30dB that cannot be removed should be investigated by a LECOM PD-LSG1 device to assess the pattern in the power cycle
This will help conclude if it is noise, as well as often allowing the user to see the PD within the noise