Testing and Commissioning

Monday, December 9, 2013

High Impedance Busbar protection CT connections

One and half scheme High Impedance Busbar protection -1

This is normal One and half scheme  bus bar protection.
1A and 1B bus bar scheme will operate separately irrespective of middle breaker or DS close or open. In this scheme the middle breaker CTs are over lapped to protect the middle breaker. Consider the 1A side breaker CT connected with 1A bus scheme and  1B side breaker CT connected with 1B bus scheme. If any fault in middle breaker it will consider as the out zone fault for both protection schemes. So the breaker is proteded by overlapping the CTs. The Disconnecter Switch (DS) contact is no need in the CT secondary circuit as like Double bus scheme.

One and half scheme High Impedance Busbar protection -2

This circuit special one and there is no middle breaker and CT. The middle DS is separate the 1A &1B bus.

There is no separate incoming  line for 1B bus and energaized through  1A bus only.

There are two condition for protection operation

1. When middle DS closed , both relay will coming into picture. Both 1A & 1B Relay will operate for fault in any bus. A disconnector 'NC' contact will open one CT earth point to maintain the single point earthing.

2. When middle DS open, 1B relay will be disconnected from the circuit and a disconnector 'NO' contact will open the CT secondary circuit in 1B side to avoid the relay operation for 1A bus fault.

Double Bus High Impedance Busbar protection -3

The CT secondary current will select the relay by DS contacts status.

1. When 1A DS closed and current will go to 1A relay through Early make and Late break  1A DS contact. If 1B DS closed current will go to 1B relay through Early make and Late break 1B DS contact.

2. If  both DS are closed and current will go to both relays. If both DS are open CT will shorted through DS 'NC' contacts.

3. During fault condition trip also selected through DS contacts to trip the particular breakers connected in faulty bus.

Tuesday, November 5, 2013


There are two 380 KV  line in the substation and both are continuously charged for three months with 70% load in summer. The load was reduced in winter and one line got shutdown. The differential relay RED 670 which is belong to shutdown get started to restart again and again and finally its comes a stage as below




1. There is no Measurement column and instant of 'RED670' , ' IED 6x0.1.0  in the top line
2. There is no previous disturbance records and Events
3. There is no inbuilt serial numbers and type
4. Ready LED glows

1. All final relay settings are corrupted there is no more data

ABB suggested the following

1. DC switch ON/OFF

But nothing will happened same status

2. Up load final relay setting files again
Already rear side fiber communication with SAS failed and laptop connected in front port and relay was communicated. But setting file can't write and read from relay.

Finally ABB come to site and find out the problem. The Central processing unit ( CPU ) cord  got failure and changed new one. Setting files are uploaded and tested. Now relay works fine.


The communication between station to station established by a separate communication system.


An OPGW cable contains a tubular structure with one or more optical fiber in it, surrounded by layers of steel and and aluminium wires. The OPGW cable is run between the tops of high-voltage Towers. The conductive part of the cable serves to bond adjacent towers to earth ground, and shields the high voltage conductors from lightning strikes. The optical fibers within the cable can be used for high-speed transmission of data for protection and control and utility's own voice and data communication.


OPGW cable will bring to bottom of the tower and spliced with Single mode Under Ground Non Metallic Fiber Optic cable in a junction box. NMFOC cable made connection between OPGW and OFMR , ( in side substation communication room ) laying through the under ground communication duct bank.
Its may be 48 core, 24 core 12 core depend upon requirement.


OFMR is a junction box to connect the NMFOC to other communication equipment. OFMR mounted in the Fiber Splicing / Termination Panel (FSTP). OFMR suitable for terminate 48 ,24 ,12 core  U/G NMFOC. Small length Pigtail fiber cable is used to connect the NMFOC and OFMR.


PATCH CABLE SPECIFICATION  FC/ PC Type connector in one end (ITU-T-G655)
PIGTAIL CABLE SPECIFICATION FC/PC Type connector in one end ( ITU-T- G655)



SDH is the total communication unit used to convert and invert the electrical signal  and voice signals to digital signal. SDH is a unit of equipments contain Converts and Digital Cross connection Panel ( DCX ), Data Voice Multiplexer ( DVM ). DVM panels are contain number of channels with FOX 515. Each chenals are specified for each purposes Protection , SCADA , Voice communication. FOX 515 connected with MDF ( Main Distribution Frame ) by useing 100 pair cable.





MDF is a signal disribution rack to connect the electrical signal wires from Protection panels and SCADA , Telephone panels.

Thursday, September 5, 2013


The concentration of SO2 is an indicator for the presence of decomposition products in SF6 gas. The SO2 measurement in SF6 gas in the GIS equipment which is energized condition is easy way to analyze the abnormalities.

Gastec Detector Tubes

Gastec Tube

Gastec Detector Tubes are used for the rapid measurement of SO2 in SF6 gas. These Pre-calibrated, direct-read detector tubes offer distinct lines of demarcation for easier viewing and color charts. Each tube contains detecting reagents that are especially sensitive to the target substance and quickly produces a distinct layer color change. 

Gastec Gas Sampling Pumps

Gastec Gas Sampling Pumps are used to take the sample of SF6 gasCollect the SF6 gas in a polythene bag from the equipment Non returnable value. Take a fresh Detector Tubes and broke two edges and fix one edge with Gas sampling pump, insert the other end  in to gas collected polythene bag. Then pull the gas Pump handle.  Now gas will accumulated in the gas tube. If SO2 presence in the SF6 gas, the tube in side Blue color will be change in to Yellow. 

Monday, September 2, 2013


Problem -1

A Circuit Breaker opened from the remote end for some outage work . After complete the work breaker was tried to close again, but "R" phase CB pole not closed and other two poles are closed . 
Immediately Pole Discrepancy Stage -1 operated and closed breaker poles are opened. 

CB was taken outage for further investigation.

1.+ve & -ve is checked across contact K1 - ok.
2. Individual coil resistance - ok
3. Function of K1 checked - ok
4. CB was closed by manually press the closing coil nob. Again locally CB was tried to close. All three phases are closed. We thought there is struck up in the close coil nob. So again CB tried to close but this time same problem happened.   

5. Resistance checked between point A & B 
R- Phase = 90 ohms Y= 40 ohms B= 40 ohms

The resistance R1 not shown in the drawing . So we desired wire problem between coil and point 'A'. Then the R1 was found between between coil and point 'A'. 

A wire connected in the resistance was found disconnected. And circuit taken full resistance value. So the enough current was not flowing through the coil to pickup. 

Problem -2

When close the CB ,  " R" Pole oil pressure comes to "0" point. Pole was not closed. Same PD- Stage 1 operated and other poles are tripped.

After long investigation found the closing coil nob is in middle position. So when ever close comment came total compressed pressure was relished thorough a valve. Then oil pressurizing  motor automatically ON but oil pressure was not increased.

 Then closing coil nob was properly pulled out. Oil pressure was increased by manually up 10Mpa. Then motor was ON and pressure got normal.

The same problem will happened if CB close with "0" pressure. 

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