English Electric Mains shut down/start up procedure

Katie_J8 · Sep 9, 2022

Hi everyone, my husband has turned up on a job with a very old mains that he will need to shut down at some stage. Does anyone know the procedure for shutting down/re starting this type of mains? Photos attached. Apologies if this is the wrong forum and thanks for reading!

[ElectriciansForums.net] English Electric Mains shut down/start up procedure

Julie. · Sep 9, 2022

Katie_J8 said:
Hi everyone, my husband has turned up on a job with a very old mains that he will need to shut down at some stage. Does anyone know the procedure for shutting down/re starting this type of mains? Photos attached. Apologies if this is the wrong forum and thanks for reading!View attachment 101397 View attachment 101398

There is not enough information there.

It's clearly an ACB, and it looks like an old EE E3, which could be 3.3kV.

If he doesn't know how to operate any item of switchgear, he should be nowhere near it.

EE used the same or similar facia for most of their range, only really adding more information/options as they got higher in voltage, by the time you get to the E7 & E8 they do look significantly different to the lower voltage stuff.

This could be a 415V or 3.3kV ACB.

Edit.

If it is 415V it could be the M-pact range, likely in a form 4 switchboard, but there is no way to be sure from these photos.

Katie_J8 · Sep 9, 2022

Julie. said:
There is not enough information there.

It's clearly an ACB, and it looks like an old EE E3, which could be 3.3kV.

If he doesn't know how to operate any item of switchgear, he should be nowhere near it.

EE used the same or similar facia for most of their range, only really adding more information/options as they got higher in voltage, by the time you get to the E7 & E8 they do look significantly different to the lower voltage stuff.

This could be a 415V or 3.3kV ACB.

Edit.

If it is 415V it could be the M-pact range, likely in a form 4 switchboard, but there is no way to be sure from these photos.

Thanks for your help, unfortunately there is no other information available.

He would not work on an item that he does not know how to operate, hence my asking for information - we're trying to find someone that has worked on these to assist - we've drawn a blank so far but hopefully your additional information may help, so thanks again.

Julie. · Sep 9, 2022

Katie_J8 said:
Thanks for your help, unfortunately there is no other information available.

He would not work on an item that he does not know how to operate, hence my asking for information - we're trying to find someone that has worked on these to assist - we've drawn a blank so far but hopefully your additional information may help, so thanks again.

It is pretty important you get the right information, English Electric made the OB3 in the 1950s - this MUST NOT BE OPERATED!

It was redesigned to be the M-pact in the 60s and EE got swallowed up by GEC in the late 60s, after this the M-pact became the GEC M-pact (now known as the mk 1) since then it's become the mk2, new M-pact, M-pact plus etc.

The ob3 and M-pact mk1 look similar when you just have the small view as your photo.

Colin Jenkins 01 · Sep 9, 2022

Katie_J8 said:
Hi everyone, my husband has turned up on a job with a very old mains that he will need to shut down at some stage. Does anyone know the procedure for shutting down/re starting this type of mains? Photos attached. Apologies if this is the wrong forum and thanks for reading!View attachment 101397 View attachment 101398

Hello Katie.
Tell your husband not to touch it. There is almost certainly high energy present (arc flash hazard); it should have been risk-assessed and labelled as such. If so, that means arc-rated PPE is essential to safely operate this circuit breaker. The lack of arc flash labelling and circuit designation labels leads me to think it has not been maintained. If the site owner does not know how to operate it, it may not have been functioned for an unknown period of time and may be unsafe. Call the DNO; they have all the right PPE to deal with it and will also be able to service and test it, which will be required. It then needs to go on a routine maintenance schedule and be risk-assessed for the potential arc flash hazard. And, usually, the lower the service voltage, the greater the arc flash hazard, so don't relax if it's found to be "only" 415 volts. Keep well away from it in the interim.
Regards,
Colin Jenkins.

timhoward · Sep 9, 2022

I've used some later descendants - GE M-Pact motor wound spring (MWS) units. The post above says it all, don't do it!

Rockingit · Sep 9, 2022

Surely, if it's MV switchgear then the owner would know if they have a massive buzzing TX somewhere?!

Katie_J8 · Sep 9, 2022

Julie. said:
It is pretty important you get the right information, English Electric made the OB3 in the 1950s - this MUST NOT BE OPERATED!

It was redesigned to be the M-pact in the 60s and EE got swallowed up by GEC in the late 60s, after this the M-pact became the GEC M-pact (now known as the mk 1) since then it's become the mk2, new M-pact, M-pact plus etc.

The ob3 and M-pact mk1 look similar when you just have the small view as your photo.

Thank you, he is going to contact the DNO, thanks for all your advice.

Katie_J8 · Sep 9, 2022

timhoward said:
I've used some later descendants - GE M-Pact motor wound spring (MWS) units. The post above says it all, don't do it!

Thanks, he is contacting the DNO, really appreciate your help.

Katie_J8 · Sep 9, 2022

Colin Jenkins 01 said:
Hello Katie.
Tell your husband not to touch it. There is almost certainly high energy present (arc flash hazard); it should have been risk-assessed and labelled as such. If so, that means arc-rated PPE is essential to safely operate this circuit breaker. The lack of arc flash labelling and circuit designation labels leads me to think it has not been maintained. If the site owner does not know how to operate it, it may not have been functioned for an unknown period of time and may be unsafe. Call the DNO; they have all the right PPE to deal with it and will also be able to service and test it, which will be required. It then needs to go on a routine maintenance schedule and be risk-assessed for the potential arc flash hazard. And, usually, the lower the service voltage, the greater the arc flash hazard, so don't relax if it's found to be "only" 415 volts. Keep well away from it in the interim.
Regards,
Colin Jenkins.

Thanks so much, he is contacting the DNO as suggested. Really appreciate the help.

Lucien Nunes · Sep 9, 2022

A wise move. Thanks for reassuring us.

A key point here is that an ACB of this type, is not something that you just operate without forethought. Even if you are skilled and familiar with the equipment, the procedure used needs to take account of the local conditions, maintenance status or lack of it, load being interrupted, prospect of closing onto a fault etc, all of which would be built into the risk assessment for the activity.

These things can be deceptive. They sit quietly for decades giving an impression of solid reliability, but without actually being called upon to perform their job and without the maintenance necessary to keep them ready to spring into action. Then, when someone finally presses the button and the neglected mechanism malfunctions, it erupts into a fireball.

Rockingit · Sep 9, 2022

Lucien Nunes said:
Then, when someone finally presses the button and the neglected mechanism malfunctions, it erupts into a massive viral hit on Youtube.

Corrected that for you.

Julie. · Sep 9, 2022

Lucien Nunes said:
A wise move. Thanks for reassuring us.

A key point here is that an ACB of this type, is not something that you just operate without forethought. Even if you are skilled and familiar with the equipment, the procedure used needs to take account of the local conditions, maintenance status or lack of it, load being interrupted, prospect of closing onto a fault etc, all of which would be built into the risk assessment for the activity.

These things can be deceptive. They sit quietly for decades giving an impression of solid reliability, but without actually being called upon to perform their job and without the maintenance necessary to keep them ready to spring into action. Then, when someone finally presses the button and the neglected mechanism malfunctions, it erupts into a fireball.

If it is an OB3 it would be dependent manual operation.

Which means it closes as slowly as you operate it!

People have been known to start opening them, halfway through closing them because they hear arcing.

It does indeed turn into a fireball.

M-pact and the E series could be independent manual, manual charged spring, motor charged spring, or solenoid.

Julie. · Sep 9, 2022

To give a small example, this is a test where I applied a small fault to a piece of switchgear with a minor manufacturing fault (deliberate), the piece of heat sensitive board to the front-left of the switchgear is the size and in the place where the operator would be when operating it.

Unfortunately although you can see the "operator" pushed back, the angle obscures the view - the material was burnt right through in places, indicating the operator could have suffered 3rd/4th degree burns to 75/40% of their body.

Vortigern · Sep 9, 2022

What are those disc things all around the room. In fact, what is that room? @Julie. And, errr, I have made a solemn promise to myself to not operate an air circuit breaker anytime soon!
P.S. And why must the OB3 NOT BE OPERATED? Is/was it defective like the above? All very interesting by the way.

DPG · Sep 9, 2022

Vortigern said:
What are those disc things all around the room. In fact, what is that room? @Julie. And, errr, I have made a solemn promise to myself to not operate an air circuit breaker anytime soon!

Look like insulators with bus bars mounted on them I think? Looks very interesting eh!

DPG · Sep 9, 2022

Julie. said:
To give a small example, this is a test where I applied a small fault to a piece of switchgear with a minor manufacturing fault (deliberate), the piece of heat sensitive board to the front-left of the switchgear is the size and in the place where the operator would be when operating it.
View attachment 101428
View attachment 101429
View attachment 101430
View attachment 101431
View attachment 101432
View attachment 101433

Unfortunately although you can see the "operator" pushed back, the angle obscures the view - the material was burnt right through in places, indicating the operator could have suffered 3rd/4th degree burns to 75/40% of their body.

You've broken that.

pc1966 · Sep 9, 2022

Vortigern said:
P.S. And why must the OB3 NOT BE OPERATED? Is/was it defective like the above? All very interesting by the way.

I think it is the "dependant operation" aspect, in other words unless you can and know how to make the damn thing operate VERY QUICKLY you get a serious arc-flash/arc-blast risk.

I'm not even sure if that is allowed any more?

pc1966 · Sep 9, 2022

A quick search finds this useful document:

https://www.hse.gov.uk/pubns/indg372.pdf

I has the requirements on page4 of:

prohibiting the operation of dependent manually-operated switchgear when live, except under very carefully controlled conditions;

And just below that:

when possible, replacing the closing mechanism for dependent manually-operated switchgear. When this is not possible, you must replace the switchgear;

pc1966 · Sep 9, 2022

I must say I was only dimly aware of some of these things but @Julie. inputs here have made the seriousness of it a really clear risk!

Lucien Nunes · Sep 9, 2022

People have been known to start opening them, halfway through closing them because they hear arcing.

To use a flight analogy, it's like trying to abort a takeoff after V1, which you only do if the aircraft is incapable of flight. It is better to continue, even if you suspect there is a problem, than to create a worse one by aborting. In an aircraft that would be a runway excursion, with switchgear it's the aforementioned fireball.

Operating open front switchgear on 250-500V DC at lower currents, you can get a clear idea of how an arc behaves according to what you do with the switch handle, without the risk of the severe arc-flash injury that comes with failed MV or HV or even high current LV switching events. IMO every electrical apprentice should get to see and feel this.

Julie. · Sep 9, 2022

Vortigern said:
What are those disc things all around the room. In fact, what is that room? @Julie. And, errr, I have made a solemn promise to myself to not operate an air circuit breaker anytime soon!
P.S. And why must the OB3 NOT BE OPERATED? Is/was it defective like the above? All very interesting by the way.

The red Yellow and blue busbars are the three phases we connected the equipment to, we could choose the voltage on those from 200V to 38kV depending upon the test requirements, the disks are insulators.

That is a test bay at a switchgear testing station, low - medium voltage, unfortunately I don't have photos of the other bays some of which go to high voltage (66kV+)

The OB3 operates like many of the era and is known as "dependant manual"

This means the speed of contact closure is completely dependent upon the operator, if you are hesitant and do it slowly or even stop and reverse, then the contacts will not make properly.

Switchgear is generally designed to close onto a fault, but opening a fault is not always required (switches), and when it is able to interrupt a fault (breaker), they sometimes use different contacts, and in any case they always need to follow the proper cycle from: contact made, contact separation, arc, arc control, then arc extinction then fully open.

Dependant manual interrupts this cycle.

As long as you make a swift closure, even on to a fault, the breaking cycle can complete safely.

As you may guess I worked at both a switchgear manufacturer and testing station , unfortunately I had to go out and investigate some incidents including a number where deaths had been involved.

I did attend one where an operator had started to close a switch (~11kV) designed in the late '40s manufactured in the 50s - so dependant manual, and realised he hadn't removed the earth links, so hesitated half way through and tried to open it.

5 out of the 6 people in the switchroom died, the one who lived was near the door managed to get out but was engulfed in the burning oil, it was horrific to be honest, one of the worst I investigated.

DPG · Sep 9, 2022

Julie. said:
The red Yellow and blue busbars are the three phases we connected the equipment to, we could choose the voltage on those from 200V to 38kV depending upon the test requirements, the disks are insulators.

That is a test bay at a switchgear testing station, low - medium voltage, unfortunately I don't have photos of the other bays some of which go to high voltage (66kV+)

The OB3 operates like many of the era and is known as "dependant manual"

This means the speed of contact closure is completely dependent upon the operator, if you are hesitant and do it slowly or even stop and reverse, then the contacts will not make properly.

Switchgear is generally designed to close onto a fault, but opening a fault is not always required (switches), and when it is able to interrupt a fault (breaker), they sometimes use different contacts, and in any case they always need to follow the proper cycle from: contact made, contact separation, arc, arc control, then arc extinction then fully open.

Dependant manual interrupts this cycle.

As long as you make a swift closure, even on to a fault, the breaking cycle can complete safely.

As you may guess I worked at both a switchgear manufacturer and testing station , unfortunately I had to go out and investigate some incidents including a number where deaths had been involved.

I did attend one where an operator had started to close a switch (~11kV) designed in the late '40s manufactured in the 50s - so dependant manual, and realised he hadn't removed the earth links, so hesitated half way through and tried to open it.

5 out of the 6 people in the switchroom died, the one who lived was near the door managed to get out but was engulfed in the burning oil, it was horrific to be honest, one of the worst I investigated.

That's really scary that.

Julie. · Sep 9, 2022

DPG said:
You've broken that.

Yup.

And I did it deliberately!

timhoward · Sep 9, 2022

A YouTube search for “breaker failure” shows a tragic case of someone presumably winding out a switch under load. (Upsetting video - they don’t survive the massive explosion)

English Electric Mains shut down/start up procedure

Katie_J8

Julie.

Katie_J8

Julie.

Colin Jenkins 01

timhoward

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Rockingit

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Katie_J8

Katie_J8

Katie_J8

Lucien Nunes

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Rockingit

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Julie.

Julie.

Vortigern

DPG

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DPG

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pc1966

pc1966

pc1966

Lucien Nunes

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Julie.

DPG

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Julie.

timhoward

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