Testing and Commissioning

Monday, December 15, 2014

13.8kv CORONA SOUND

A corona sound was continuously coming from 13.8 kV Bus Tie side.

The complete showdown was taken for investigation. Incomer and Bus tie breakers are 3500A capacity rated and Fan is provided for reduce the heat developed in the breaker during full load condition.

The Fan wire was slightly touch the bus.




Tuesday, May 6, 2014

HIGH VOLTAGE CABLE TEST

1.CABLE TEST MANUAL

DOWNLOAD

2. CABLE CROSS BONDING CONNECTION

 DRAWING
















When current is flow through the cable a induced current will develop in the cable sheaths. This induced current will oppose the cable current. The cross bonding connection is used to neutralized the induced current. The cross bonding connection is explained in the above drawing. Cable sheath is terminate in various places and connected as cross connection 'R' sheath to "Y" sheath and 'B' sheath to 'R' sheath through resistors. Three phase voltage is applied in one end of cable and other end of cable is grounded. Short circuit current will flow through the cable and induced current in sheath will be measured by clam meter. If the current is zero in all three phase and cross connection ok .

3. FIELD TEST REPORT

1. ELECTRICAL TEST 

2. HV TEST 


Related Photos 



CABLE SHEATH CROSS BONDING CONNECTION




HV TEST READING FOR 115KV XLP CABLE TEST 


CABLE CONNECTION POINT FROM GIS 




CABLE CONNECTION POINT FROM INSIDE GIS 





CABLE CONNECTION POINT FROM CABLE SIDE




Generator Field current controller. During cable short circuit test ( Cross bonding verification) generator current increase and voltage decrease. This equipment used to control the output generator voltage by control the generator field current.



This equipment used for low voltage level cables. Very low Frequency ( VLF) method of HV test.





                                                 SEC STANDARD FOR CABLE HV TEST  


 
                                             

Monday, May 5, 2014

LINE CHARGEING & CHARGING CURRENT



Substation 2 is energized from Substation -1. The current measured in Sub -1 side is 350 Amps in both Line differential relay and Metering panel.

The current measured in Sub -2 side is 270 Amps in Line differential relay and 350 Amps in Metering panel.

The difference in the primary current in both side relays due to underground cable in the line.

Relay measure the line current and cable charging current separately.

RED 670 -ABB will shows both current in the measurement display.

Micom 546 consider charging current as a differential current.


One End current 



Remote End current 



Differential and Charging current 






Note : 

The power direction

Import should be (-ve)
Export should be (+ve)

If Micom 546 shows Export MW as a -ve value go to MEASURE'T SETUP - MEASUREMENT MODE and SET '0'

  

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

RED 670 FAIL

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

NORMAL RELAY MAIN MENU 








DEFECTIVE  RELAY MAIN MENU 

 

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.





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THIS IS SHIVA T&C ENGINEER IN NCC LTD - SAUDI.