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Topic Title: dc tripping unit for HT
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Created On: 06 March 2013 12:07 PM
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 06 March 2013 12:07 PM
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jackdaniel

Posts: 69
Joined: 29 November 2012

What is DC tripping unit?,
 07 March 2013 09:46 PM
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dlane

Posts: 681
Joined: 28 September 2007

Depends on the manufacturer and the type of switchgear.

It can consist of anything from the battery system, protection relays, interlock circuits and tripping coils or combinations of the above.

It will be responsible for tripping the latch mechanism holding the primary circuit contacts closed.

Kind regards

Donald Lane
 08 March 2013 03:37 AM
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jackdaniel

Posts: 69
Joined: 29 November 2012

Originally posted by: dlane

Depends on the manufacturer and the type of switchgear.



It can consist of anything from the battery system, protection relays, interlock circuits and tripping coils or combinations of the above.



It will be responsible for tripping the latch mechanism holding the primary circuit contacts closed.



Kind regards



Donald Lane



Hi Donald,

wht is the voltage of the battery percell?, the dc voltage for relay usually is 30V DC
 08 March 2013 10:32 PM
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dlane

Posts: 681
Joined: 28 September 2007

Personally I have never come across a 30V system.

I have seen 24V and 48V systems that were derivatives of 12V battery cells.

Larger systems I have worked on have been from station battery systems of 120V or 220V. The cell voltages for these systems was 1.2V sealed lead acid or wet cells.

Kind regards

Donald Lane
 09 March 2013 01:36 PM
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ArthurHall

Posts: 735
Joined: 25 July 2008

30V DC used to be very common in distribution substations. To me a DC tripping unit is a self contained charger/battery unit. In distribution substations they are often a wall mounted unit apox 900 wide, 500 high by 300 deep. The tripping unit is fed from a 13A socket or 20A DP switch and there are one or two out going circuits.
 10 March 2013 06:50 PM
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JonathanHill

Posts: 225
Joined: 09 September 2002

Many ground-mounted secondary substations use self-powered relays and tripping coils (with the necessary power derived from the protection CTs).

When Emergency Tripping facilities are needed (eg when the customer takes a supply at 11kV), the power supply for this is frequently derived from a capacitor which is charged from the metering VTs.

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Jonno
IET » Energy » dc tripping unit for HT

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