RJ 45 SHIELDED CABLE CAT 6

The CAT 6 shielded cables are used for Substation communication.

RED 670 INPUT CARD REPLACE

1.Switch off the DC 

2. Remove the plugs and CT & VT wires

3. Remove the screws with suitable driver 

4. Remove the cover 

5. Dismantle Input cord carefully 

6. Check the version of the card

7. Reassemble the relay and check the card availability in the Hard ware menu

MAIN ACDB INTERLOCK ISSUE

Generally the contacts used for interlocks should be direct or high speed contacts. We faced a problem in Main AC distribution panel. 

Auto transfer scheme ( ATS) 

As per ATS scheme consider  incomer CB trip due fault then Bus tie should not close in both Automatically or manually.

Same condition if  Bus tie trips incomers should not close in both Auto/Manual condition.

Problem faced Site:

1. Both Incomers are closed and Healthy. Incomer -1 tripped by jumper and tie was automatically not closed. But trip was given by actual current injection and bus tie closed. 

2. Now Incomer -1 and bus tie is closed and Bus tie tripped by jumper and Incomer -2 was automatically not closed. But trip was given by actual current injection Incomer -2  closed.

Same happen for Incomer -2 and Bus tie combination. 

The breaker trip Aux. contact is in serious of other Breaker closing path. This contact should immediately open and block the other CB closing.

But in our circuit tripping Aux contact will pick up a auxiliary relay and this relay contact open the other CB closing path. But pickup time of this relay is little bet  high . During this pick up time adjesend CB was closed. 

So found that problem and replace high speed Aux relay.

Battery Bank Recharging Problem

The  battery System have 58 Cells and nominal voltage will be 125V DC. One day the 380 Volts Battery charger input AC supply was tripped and load was taken from battery bank.

The system voltage was reduced up to 90 V DC . 

The 380 V AC MCB was reset and Battery start to charge again and drown 450 Amps.

Normally this current should gradually reduce to normal value      70 -80 Amps. But 450 Amps continuous for 4 ,5 hours. The cooling system alarm fail was appeared.

We arranged extra fans around the Charger. With in half-an hour current start to reduce gradually and become normal value.

RED 670 TEST PROCEDURE BY Mr.OMER

Mr. Omer is by best friend presently working in XERVON - Saudi

He write a best article about How to test the Differential Relay RED 670.

He is given this article free for beginners. 

Link to download 

Note : I hope your not  miss use this article 

TRANSFORMER HV BUSHING PF VALUE

Make : CG  Transformer
Rating : 67 MVA -  380/115/13.8kV

The Power factor value  HV side bushing should be below 0.5%.

But during our testing the value came around 1.45%.

Our Transformer Fourmen  top bushing. The bushing is connected with flexible conductor and immersed with the oil. He tight this connection and clean the area around.

We conduct again same test and result is with in the limit 0.3%.

HV busing 

Test value after tight and clean