Megger Malaysia

24/11/2023

CABLE SHEATH FAULT LOCATION

Cable sheath fault location is the final stage in this process, pinpointing the flaw on site. Faults can be identified by ground fault locators, which pass a test current along the cable and measuring the voltage gradient at the point it exits to ground.

Since many years the main reason of faults in cables with plastic insulated outer
sheath is the damage of this sheath. This permits the pe*******on of water into
the cable and as a consequence it enhances the growth of "Water Trees“ and
other corrosion based damages in power cables. Water trees are one of the
primary reasons of cable faults.

In cables, which are not protected against longitudinal water migration there is
the additional danger of joint faults due to water spreading though the
conductors into the joints.

Why Sheath testing ?

A perfect, non disturbed operation of a cable system requires in addition to the stated requirements for data transmission and energy transfer, good insulation values between the conductors as well as between conductors and shield. Prerequisite for this is also the intact outer sheath (Jacket), which is today mostly consisting of PE.

The damage statistics of cable faults published in the recent years, especially for
medium voltage cables, indicated a significant amount of sheath faults, which were
obviously the triggering cause for a breakdown of the cable.
Resulting the sheath testing permits in a certain context also a diagnostic information
about the condition, resp. the expectable state of the cable.

Additionally the sheath test is one oft he most important tools in combination with all diagnostic technologies, since a diagnostic evaluation of a cable requires that the
cable to be tested has to be in a good and faultless condition.

A diagnose without a combined sheath test is a relatively unreliable valuation of the cable condition, since entering water as a result of a sheath fault and the following damages result in a fast decrease of the condition quality.This again will decrease the value and reliability of any diagnostic evaluation.

The test of the integrity of the outer sheath provides almost the ideal condition for the early detection of damages and provides the possibility of an early elimination of
beginning cable faults.
With a simple insulation and voltage breakdown test between cable shield and outer
soil, it is already possible to conduct a commissioning test directly after laying and to confirm the integrity of the outer plastic sheath. With regular tests, especially in areas with high construction activities, it is possible to detect damages of the outer sheath at an early stage, where an immediate repair will prevent further damages, and where it is still possible to locate the cause of the damage and to claim an according compensation.

A sheath damage, if not associated with a direct damage of the cable insulation, will seldom lead to a fast breakdown and failure of the cable installation.
From the moment of damage until the appearance of the real breakdown, many months or even years can pass.

If the sheath is damaged by a manual impact or a by penetrating stone, the shield
beneath can be driven more or less through the semiconducting layer into the
insulation. In this location the homogenous field distribution is distorted and partial
discharge sources develop. This partial discharge will then, depending on its intensity, destroy the insulation and lead to a breakdown.

COME INTO THE PICTURE;

Megger plays the role by inventing Mobile, battery operated sheath fault
location system (MFM10-1) which intuitive menu-driven operation and automatic measurement and evaluation system enables cable sheaths to be tested and sheath faults to be pre-located and pinpointed as simply as possible. Data is entered using the proven Megger rotary encoder principle and is supported by a touch screen.

Click here Datasheet >> https://uk.megger.com/sheath-fault-location-system-mfm10

For Consultation and Quotation please feel free to contact us..

17/11/2023

POLARIZATION INDEX (PI) TEST
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Polarization Index (PI) test is basically performed at the same manner as Insulation Resistance (IR) test.
IR test is performed for a period of 1 minute, whereas PI test is performed over a period of 10 minutes. This gives the absorption (polarization) current ample time to decay, and reveals detailed indication of the total leakage and conduction current.
PI normally used in inductive specimen as an indication of winding contamination, moisture ingress (leakage currents), and/or bulk insulation damage (conduction currents).

COME INTO THE PICTURE,

Megger provides features of PI parameters for operator to predict failure of a specimen in early stage.

We offer various of model number according to user application.

Contact us for Free Consultation and Quotation.

15/11/2023

Recommended circuit breaker tests
By Megger

[Timing and Travel]
Testing used to determine and validate the performance characteristics of circuit breakers. For example, the changing state of main and resistor contacts (open- close, close-open, etc.) and auxiliary contacts (e.g., 52a and 52b) versus time, varying defined distances traveled by the main contacts (e.g., total travel, over travel, rebound, stroke, and contact wipe), velocity (average and instantaneous), dwell-time and dead-time, are primary circuit breaker characteristics measured.

[Motion]
See timing and travel above. The contact travel motion is captured by connecting a travel transducer on the moving part of the circuit breaker’s operating mechanism or interrupter and is used to assess the condition of the interrupter, damping units and identify mechanical issues with the operating mechanism. The motion is presented as a curve displaying distance vs. time. Several parameters are measured. For example, over travel is the distance traveled by the contacts that exceeds their final resting position and is measured to verify the proper operation of the damping assemblies within the breaker. Measured values from the motion curves are compared to reference data provided by the circuit breaker manufacturer.

[Coil current]
This measurement can be performed online or offline and is used to detect potential mechanical and/or electrical problems in actuating coils well in advance of their emergence as actual faults, and extract information about lubrication and latch operation. The quality of the control voltage supply is also detectable from these tests. This diagnostic is perhaps most effective when it is performed as a "First Trip" activity. First Trip is performed when the circuit breaker is in-service, and has not been operated for a long time. Lubrication problems are easiest to identify in this scenario. Comparison to previous results is the best method of analysis.

[Static (contact) resistance measurements (SRM) ]
Micro-Ohm measurement of the main contacts. This test is conducted by injecting DC current through the breaker main contact system when the circuit breaker is closed, and measuring the voltage drop so that the resistance can be calculated. The resistance reflects the condition of the conducting parts.

[Dynamic (contact) resistance measurements (DRM) ]
This test is used to determine the length and condition of the current carrying part of the arcing contacts in SF6 puffer type circuit breakers. DRM tests are conducted by injecting DC current through the breaker main contacts while the breaker is operated. The breaker analyser then calculates and plots resistance as a function of time. If contact movement is recorded simultaneously, the resistance can be determined at each contact position. With DRM measurement, the arcing contact length can be reliably estimated. The only other means to do this is by dismantling the circuit breaker. In SF6 breakers, the arcing contact is commonly made of a tungsten/copper alloy and is burned off and becomes shorter for each interruption of current.

[Vibration]
Non-invasive testing that is based on the premise that all mechanical movements produce sounds and/or vibrations, and that by measuring them and comparing the results with previous test results, the condition of the equipment in question can be evaluated. The breaker can stay in service during the test. Using an accelerometer, an Open-Close operation is analysed. The first operation can be different than the second and third because of corrosion and other metal to metal contact issues. The vibration method detects faults that may barely be indicated with conventional methods and is published in CIGRE and IEEE papers.

[Motor current]
Applicability of this test is dependent on the circuit breaker’s operating mechanism. A measure of motor current is only applicable on spring drives.

[Minimum pick-up measurement ]
It is minimum voltage to operate circuit breaker. This test is intended to determine the minimum voltage at which the breaker is able to operate – the contact timing parameters are not of interest, only whether the breaker operates or not. It is a measure of how much force is needed to move the coil armature. Testing begins at a low voltage, sending a control pulse to the breaker. The voltage is increased by small increments (5 V) until the breaker operates; this voltage is recorded and is expected to remain unchanged through future dates.

[Minimum voltage]
This test is specified and recommended in international standards. The objective of this test is to make sure that the breaker can operate at the lowest voltage level provided by the station battery when the breaker has to operate during a power outage. The test is performed by applying the lowest specified operating voltage and verifying that the breaker operates within specified operation parameters. Standard test voltage is 85% (and 70%) of nominal voltage for close (and open).

[Station voltage]
It is recommended to measure the voltage level of the battery or power supply while operating the circuit breaker in order to verify that the CB is performing to desired specifications. If the voltage level is low or not correct, one might accidentally adjust parameters on the breaker when the cause of malfunction is the power supply.
Power factor/dissipation factor/ tan delta and capacitance
Provides means for verifying the integrity of the insulation for circuit breaker components.

[Vacuum bottle test]
Applicable for vacuum circuit breakers. The vacuum bottle is tested with high voltage AC or DC to check that the integrity of the vacuum is intact.

[SF6 leakage]
Applicable for SF6 circuit breakers. Using gas leak detectors (sniffers) or thermal imaging, SF6 leaks are sought. These may occur in any part of the breaker but are more commonly found where two parts are joined together such as valve fittings, bushings and flanges. There may be porosity leaks as well, whereby the actual tank is leaking, but this does not happen often.

[Moisture/Purity]
A small amount of SF6 gas is vented from the breaker through a moisture/purity analyser to determine the moisture and concentration of the gas. It is important that the moisture content inside an SF6 breaker is kept to a minimum as it can cause corrosion and flashovers inside the breaker. When there is arcing (i.e., faults or normal interruptions) inside of the circuit breaker, the SF6 combines with water to produce corrosive by-products.

[Air pressure test]
Applicable for air-blast breakers. Air pressure level, pressure drop rate and air flow are measured during various operations.

COME INTO THE PICTURE....

Megger offers solutions in Circuit Breaker Testing...
Please contact us for free consultation...😎

10/11/2023

Why perform discharge
testing?

Capacity test is the only way to get an accurate value on the actual capacity of the
battery.
When used regularly it can be used for tracking the battery’s health and actual
capacity and estimate remaining life of the battery.
During the test it is measured how much capacity (current x time expressed
in Ah) the battery can deliver before the terminal voltage drops to the end of
discharge voltage x number of cells. The current shall be maintained at a constant
value. If the battery reaches the end of discharge voltage at the same time as the
specified test time the battery’s actual capacity is 100% of the rated capacity.
If it reaches the end of discharge at 80% (8 h) or before the specified 10 h, it shall
be replaced.

Here we share how to size up battery load tester for your reference.
The following questions need to be pop up;

1. What battery strings do you test?
Eg: 24V, 48V, 125V, 240V, 380V, 480V or others

2. What is max discharge current for each string do you require?
Eg: 100A for 48V and 100A for 125V

3. How many batteries do you test in one string?
Eg: 24 cells of 2V in 48V string, and 60 cells of 2V in 125V string

Then we could decide how many load we require to use.

COME INTO THE PICTURE.....

TORKEL 900 series is used to perform load/discharge tests which are the only way to determine battery systems actual capacity. Together with the cell voltage logger, BVM, connected directly to the TORKEL 900, it becomes a complete, stand-alone,discharge test system.

Please contact us for Free Consultation...

07/11/2023

Ready to save hours and hours on your circuit breaker testing?

Efficient testing procedures are crucial in the rail industry. Imagine if there was a way to significantly reduce the time spent testing DC high-speed circuit breakers while maintaining accuracy and effectiveness.

Well, now there is!

Our latest video shows the ease of use and unmatched efficiency of Megger's BALTO circuit breaker test set.

Discover the performance and characteristics of your DC breakers in no time

06/11/2023

Safety and reliability in the rail sector with BALTO

Megger prioritizes safety and reliability in everything we do. Our solutions are designed with comprehensive safety features and broad functionality. See for yourself how BALTO stands out in terms of safety.