Electricity in UK Collieries.

[John]

So that the none mining types and those not familiar, I'll post the voltages in regard to electricity in UK mines.
When I started in the early 1960's, most if not all NCB pits used 3.3kv, (3300 volts) as the standard high voltage supply from the surface, down the shafts and transmitted around the workings.
Trunk conveyors were usually 3.3kv motors and switchgear.
Face equipment was a max of 550 volts NCB spec standard.
Some pits, depending on the unit engineer, either fed a tailgate transformer close to the face and one in the maingate to split the face load equally. Transformers back then were oil cooled and had flameproof breakers on the primary side, either oil circuit breaker, (OCB), or air circuit breaker, (ACB). On the secondary side was just the protection equipment, earth leakage/overloads with a low voltage circuit to trip the high voltage OCB or ACB. Secondary voltage as stated was 550 volts. At that time the max voltage allowed by law at a face was 660v.

Power was then fed to gate end boxes to NCB spec set up as banks of contactors, all flameproof, for pumps, face conveyor motors, coal cutter, shearer, stage loader, spares, and 110volt flameproof hand drills for rippers and stable hole men.

Later towards the mid to late 60's, flameproof air cooled transformers started replacing oil filled transformers and the Inspectorate granted exemptions to the use of 1100 volts at the working face. The use of electronics was starting to come into mining, with that was sensitive earth leakage equipment that limited the faults to milliamps instead of amps in faults.

Mainroad lighting was by flameproof fluorescent lights and flameproof incandescent light fittings, fed via small armoured cables with 110 volts.

The 1960's was also the time when strides were made to eliminate the conveyor attendants with automatic conveyor equipment, relieving men from the tedious job of sitting and watching a drive head all shift, he now patrolled the belt and cleaned spillage up as needed.
Control became a centralised function, where one man controlled all trunk conveyors from one point while being able to monitor all safety functions of all conveyors under his control.

Newer mines later installed 6.6kv as the high voltage of choice.
With those voltages came the Brush SF6 high voltage flameproof circuit breaker, based on inert gas to extinguish the arc when opening.
From 250KVA transformers to 600KVA and larger transformers were on their way underground.

[John]

Low voltage devices. Those were usually bare wire signalling circuits for rope haulages, all classified as "intriniscally safe" Which means they cannot produce a spark hot enough to ignite a methane/air mixture.
Other low voltage circuits were for conveyor signalling circuits and health monitoring circuits of conveyor systems underground and automatic shaft skipping equipment.
Supplies were provided by small flameproof transformers with a suitable none inductive resistor in one leg of the secondary of the transformer to limit the output current.

Telephones use special devices in the circuit to shunt dangerous currents.
Older telephones used were magneto type with two certified 1.5 volt cells to power the voice circuits.

Modern mine communications now are usually approved type mine intercom systems that can be routed through a control room. They can be cross patched into telephone circuits to enable staff to make outside calls in emergencies.

[dazbt]

"Low voltage devices. Those were usually bare wire signalling circuits for rope haulages, all classified as "intriniscally safe" Which means they cannot produce a spark hot enough to ignite a methane/air mixture."

Read this and had a thought, I can't for the life of me remember what arrangement there was on the 'bare wire' signaling system on the face-line that prevented the bell wires from being broken everytime the conveyor was snaked over, I should have paid more attention I suppose, can anyone remember?

Huwood had a concentric cable pull wire signalling system, fail to safety, in the 50's for face AFC's Daz. That was about one of the earliest manufatured systems. I think before that, pits used to come up with their own hybrid systems of pull wire, switches and "I.S." controls.

[John]

Jul 18, 2008 7:13:50 GMT -5 dazbt said:

"Low voltage devices. Those were usually bare wire signalling circuits for rope haulages, all classified as "intriniscally safe" Which means they cannot produce a spark hot enough to ignite a methane/air mixture."

Read this and had a thought, I can't for the life of me remember what arrangement there was on the 'bare wire' signaling system on the face-line that prevented the bell wires from being broken everytime the conveyor was snaked over, I should have paid more attention I suppose, can anyone remember?

To my knowledge, bare wire signalling was never used on face lines Daz. Rope haulages yes, main road conveyors before the introduction of pull wires and lockout switches.

The new manrider at Clifton had backup barewire signalling in case the inductive loop system failed, that was around 1965'ish.
I don't even recall if Cotgrave had one when I was there.
I do remember the shocks I had off of them though, even though they were 15 volts and supposed to be I.S.!

[John]

Layout of the high voltage system.

The main surface switchgear in older pits was usually located in a room at the back of the electrical workshops, in newer pits near the main switch yard. Then a high voltage feeder would go down each shaft to a main substation around the pit bottom area.
From the pit bottom circuit breakers two feeds would be run inbye to various high voltage sub stations, for transformation down to suitable voltages, ie 3.3kv/1.1kv/550 volts/110volts for lighting.
Some collieries had ring mains, thats where both legs terminate inbye and are paralleled up to spread the load out on both feeders equally.
The termination point would be through a locked oil circuit breaker, that gives a means to isolate each leg in the event of a fault on one feeder. That way power can be restored to the inbye workings until the fault is rectified.
Whether a colliery had seperate feeders or a ring main was at the discretion of the unit Electrical Engineer, some thought it presented a danger to his electricians, others thought their electricians were competent enough to handle a ring main.

Some mines also had high voltage power factor correction capacitors inbye to assist the surface power factor correction device, usually the main ventilation fan motor.

[John]

Face signalling systems.
The ones early in my career were just a signal/lockout key mounted every seven yards along the face. The cabling terminated into each box by a brass multi pin plug.
Each box had a lockout key to lock the conveyor off, and a signal button, using a code of signals the conveyor attendant, (switchman/button man) knew roughly who had stopped the conveyor.
1=STOP Followed by a station signal.
2=START Preceeded by the same station signal.
Station signals.
3= Facemen.
4=Stablehole M/G
5=Stablehole T/G
6=Electrician.
7=Fitter
etc as example.
The boxes also had a "telephone jack" on the front of the boxes, for a sound powered single hanset that was both a mike and earpiece.
At the M/G end was an approved control unit and a valve, (tube) audio amplifier and weather proof speaker for communications, the switchman had a telephone style handset.

Late face systems came into play as electronics became approved for use underground.
Two early systems were the Winster WICAS syatem, and the Davis of Derby SIVAD system.

Both had large flameproof consoles mounted onto the GEB's as part of the switching bank.

Winsters first units contained start and stop circuits for the stage loader and face conveyor, both had different pre start alarms to warn the men of an impending start up.
The unit consisted of several low voltage regulated I.S supplies, signalling circuits using tone generators, a fail to safety lockout system, an audio amplifier for communicating with the men on the face and health monitoring.
The face equipment was lockout keys mounted every seven yards along the face, with every fourth being a self contained amplifier unit with microphone on a coiled cable and mike bracket. These were changed out for units that contained the mike internally.
The system had an indicator on the console to let the switchman know where a lockout had been put in.
It operated on a crude system that seemed to work, MOST OF THE TIME! It was a wheatstone bridge circuit with the lockout indicator circuit being one leg of the wheatstone bridge. It did present some problems.


The other sytem was the Davis SIVAD system, very similar in operation, but the lockout indicator used tone generators instead of the wheatstone bridge of Winsters.
It won out in sales and became the industry standard for years.


Then Derby Automation Consultants came out with the DAC Composite Control System, competitor to Davis.

[inbye]

Interesting stuff there, John.

Could you confirm something? I remember the surface (main) fan being shut down one holiday for maintenance. Apparently, to restart it, they had to wait till the early hours & phone the electricity board, to synchronise the extra juice needed. Was that right?

If so, what about the motor for the winding engine? there didn't seem to be much difference, size wise. From memory, I'd say the fan motor was 4'.0" to 4'. 6" diameter. ( I realise there's more than size to it)

[John]

Gate End Boxes.

The National Coal Board, (nationalised coal industry) designated standards, so GEB's were of two types when 1100 volts was approved at the working face. Type1 and type2.
The type ones were rated at 400-600 volts and had a tapped control transformer inside so the electrician could set the unit to the correct working voltage.
Type2 was rated 1000-1100 volts and as per above.

The physical difference was size, the type 2 was slightly larger so as they couldn't be accidently bolted to a type1 bank of GEB's.

When I started in the industry the makes were, Metropolitan Vickers, AEI, Joy, M&CS, Belmos Peebles, Wallacetown and Baldwin Francis.
Last two UK manufacturers are Wallacetown and Baldwin Francis.
Both make multi motor flameproof load centres now as well as single Gate End Boxes.
Wallacetown with their P range and A range boxes were one of the dominant companies of the 80's with their P50, P150 boxes and A67 and A69 geb's.
B&F were probably the Rolls Royce of mining switchgear with easily maintained equipment, to say I prefer Baldwin Francis over Wallacetown is an understatement!
I'll upload some photos of both at a later date.

Although not GEB's I'll include Belmos Peebles high voltage starters. Usually used as 3.3kv conveyor belt starters, these flameproof units came as vertical and horizontal, both were also used on rope haulage starters with built in control gear.
They were also easily adapted as continuous miner control panels.

[dazbt]

"The boxes also had a "telephone jack" on the front of the boxes, for a sound powered single hanset that was both a mike and earpiece."
It might well be my memory playing me up, but I'm almost certain that I've worked on faces that had the double bare wire system, prior to the first lockout boxes, in fact (I think) there were phones that had crocodile clips exactly like the later models with the jack plug, rubber encased things, pear shaped, either way I remember the later lockout stations coming into being, then the first face tannoy systems around 67, I think South Kirkby Colliery had the first system around the Barnsley area.

[dazbt]

Jul 18, 2008 11:42:38 GMT -5 inbye said:

Interesting stuff there, John.

Could you confirm something? I remember the surface (main) fan being shut down one holiday for maintenance. Apparently, to restart it, they had to wait till the early hours & phone the electricity board, to synchronise the extra juice needed. Was that right?

If so, what about the motor for the winding engine? there didn't seem to be much difference, size wise. From memory, I'd say the fan motor was 4'.0" to 4'. 6" diameter. ( I realise there's more than size to it)

Not the same question, but it reminds me about something that I that I always wanted to ask but never did, I was once told that if Rossington Colliery didn't start to run their belt conveyors at a certain time, or if the conveyors were stopped for any excessive length of time the cost of the pits electricity usuage was actually a lot higher than when everything was running at full capacity.

[John]

Jul 18, 2008 14:12:56 GMT -5 dazbt said:

"The boxes also had a "telephone jack" on the front of the boxes, for a sound powered single hanset that was both a mike and earpiece."
It might well be my memory playing me up, but I'm almost certain that I've worked on faces that had the double bare wire system, prior to the first lockout boxes, in fact (I think) there were phones that had crocodile clips exactly like the later models with the jack plug, rubber encased things, pear shaped, either way I remember the later lockout stations coming into being, then the first face tannoy systems around 67, I think South Kirkby Colliery had the first system around the Barnsley area.

I don't recall any of those Daz, The lockout keys with sound powered personal mike/earphone was around at Clifton before I started there, several years I was led to believe. The board had used Clifton as an experimental pit since nationalisation. One of the first to have the AB shearers, AFC etc. From what I've been told, the pit had had every type of mechanised face machinery ever brought out by AB and BJD, including Meco-Moore slicer loaders.
The first Winster signalling system was installed on 12's face, that was around 1964/5.

[John]

Jul 18, 2008 14:21:03 GMT -5 dazbt said:

Jul 18, 2008 11:42:38 GMT -5 inbye said:

Interesting stuff there, John.

Could you confirm something? I remember the surface (main) fan being shut down one holiday for maintenance. Apparently, to restart it, they had to wait till the early hours & phone the electricity board, to synchronise the extra juice needed. Was that right?

If so, what about the motor for the winding engine? there didn't seem to be much difference, size wise. From memory, I'd say the fan motor was 4'.0" to 4'. 6" diameter. ( I realise there's more than size to it)

Not the same question, but it reminds me about something that I that I always wanted to ask but never did, I was once told that if Rossington Colliery didn't start to run their belt conveyors at a certain time, or if the conveyors were stopped for any excessive length of time the cost of the pits electricity usuage was actually a lot higher than when everything was running at full capacity.

Sounds a little odd Daz, but not impossible. The main ventilation fan should have been an auto syncronous motor though, it's job was to provide a steady torque for the fan load and to correct power factor. They can be adjusted watching a PF meter mounted close by while the adjustments are made.

Latter pits had a different set up, automatic capacitors that switched capacitors in and out as needed to keep as near a unity PF as possible. Electricity utilities don't like bad power factors, they charge more if you don't correct a problem per KWhr.

[tjsw]

john u forgot the old reyrolle GA1's
was cliftons # 1 choice of pre ncb spec geb
was everywhere
had funny balaced impedence pilot circuit

[John]

Dec 3, 2008 4:12:43 GMT -5 tjsw said:

john u forgot the old reyrolle GA1's
was cliftons # 1 choice of pre ncb spec geb
was everywhere
had funny balaced impedence pilot circuit

There's a few things I forget Trev, what about the other HV OCB?? What make were those?? Reyrolle too?
I didn't mention the Met Vick HV belt starter system either, remember the "table" top reversing starters? The new manrider used one and 1s No1 belt, old 2s No2 had one too.
Plus what switchgear did the Cable Belt have?? I know it was a slip ring motor driving it with flameproof resistance starter.
Then the only none flameproof motor in the pit was the Stone Head rope haulage.

[tjsw]

was real old mavor&colson
same outfit that made mc3 loader and samson coalcutter

trev

[John]

The only M&CS switchgear I've ever come across Trev, apart from that mounted on the M&C3 loaders, was a GEB at British Gypsum's Marblaegis Mine. There was also an old Joy GEB there too.

I do recall on the returns, off the bend and start of 15's where the new manrider was installed, just through the air doors was a pump and an alloy GEB that "wasn't on the books" I'm surprised that Lol hadn't had that one scrapped!! I have no idea what it's make was now.

[John]

Trev, wasn't the Reyrolle GA1 an OCB?? The one with the square headed screws in the E/L reset cover??? I still have a couple of square drive keys, I'm sure they were for Reyrolles, I still have my Met Vick triangular key too, plus the old B&F test key and a couple of Whecol keys.
Somewhere in a toolbox is a No1 padlock!!! Recall those?

[alanvickers]

I have just joined the forum so I am picking up on some earlier postings.

In response to John's posting No 1, when I first started work at Silksworth Colliery in September 1949 there was already an electricity supply of 6,600 volts going underground and this went to each of the inbye sub-stations. There were duplicate supply cables down the shaft and duplicate supply cables from the shaft-bottom sub-station at the Maudlin Seam and going inbye from there as far as a main sub-station located about 1.5 miles inbye. I am unsure when all this had been done but I am guessing that it may well have been shortly after Nationalisation or even shortly before. I never got the impression that this had been very recently completed so perhaps it was shortly before. As far as I am aware this was the only colliery in the area that had a 6.600 volt supply underground, all other collieries had either 2,750 or 3,300 volts supplies.

At one time Silksworth had generated its own electricity in quite a large power station. In 1949 it was taking a supply from the North Eastern Electricity Board (NEEB) and previously (I think) from the North Eastern Supply Co (NESCO). This was at 20,000 volts and there were two 20,000/6.600 volt step-down transformers which were owned by the National Coal Board.

All switchgear, 20,000 and 6,600 volt was of Reyrolle manufacture, the main distribution board on the surface was Reyrolle 'LA' type and the underground switchgear was some quite old Reyrolle 'C' type at the Maudlin shaft-bottom sub-station with all other underground 6,600 volt switchgear of Reyrolle 'E' type. I cannot recall the exact type of the NEEB switchgear - it was quite old switchgear at that time but in about 1954 a new switch room was built with more modern Reyrolle switchgear installed

Each foreman and two or three electricians were licensed by the NEEB to operate the 20,000 volt switchgear, under telephone instruction from their Central Control Engineer, in later years, from 1955 - 1960, I was so licensed.

There was no form of power factor correction equipment in use.

At that time gate end boxes were of MetroVick manufacture in some parts of the pit - MU80 & 81s & a few MCU 150s for coal cutters and conveyors with MU11's for drilling machines - these had a frequency changer inside and were used with drilling machines of Victor Products make that were supplied with 110 volts at a higher frequency. In other parts of the pit Reyrolle GA8s were used for coll cutters and conveyors and GA9s for drilling machines - of HuWood manufacture. Later a few HuWood GEBs were introduced for drilling machines.

There were a few Belmos type PNS units for small pumps etc, later some Belmos type FDOs were brought in for this sort of use.

In about 1956/7 we got the first GEB's to NCB standard specifications - mainly of Wallacetown (Wecol) manufacture but later some Belmos type SGU2s came along.

Some Baldwin & Francis GEBs were introduced into the pit in the early 1960s but this was after I had left.

The underground power transformers were generally made by Bruce Peebles and had a capacity of 200 kVA. In about 1959 all were fitted with a reactor connected between the neuttral point of the secondary winding and earth, this limited the current that could flow in the event of a fault to, I think, 5 amps. At that time there were many GEBs in use that did not have either earth leakage or sensitive earth leakage protection.

In response to Dazbt posting No 9 NEEB had a 'maximum demand indicator' which clicked in at a particular time each hour. The maximum readings on this indicator during one quarter determined the electricity charges for the next quarter. We knew the time that this indicator clicked in so we always tried to make sure not to start large electric motors, such as the fan or compressor motors at that time so that their high starting currents did not affect the maximum demand indicator and so increase our electricity costs.

In regard to the Reyrolle GA1 mentioned in the last posting, this was a fairly tall air- break gate-end box

As for signalling on the coal face I never came across any bare wire systems in use. The first real signalling system was one made by GEC that had an intrinsically safe bell and pull-switch housed inside a steel box together with an approved dry battery of GEC make. A small diameter wire rope ran along the coal face to a drum and tensioning uit which was mounted at the tail gate end. The pull switch had contacts to ring the bell and also to interrupt the pilot circuit of the conveyor so pulling on the wire rang the bell and simultaneously stopped the conveyor. These units were introduced some years before the HuWood systems came along and I seem to recall that they were first used with armoured conveyors and shearers.

AlanVickers.

[John]

I only recall Reyrolle HV (3.3KV) OCB's Alan, can't for the life of me recall the type numbers as most of the OCB's I worked with were Met Vicks way back.

[John]

I'm going to be posting pictures of some of the older equipment on the website to this forum fairly soon, an M&CS gate end box, some older Met Vicks, SF1 OCB etc. There seems to be nothing I can find on the internet regarding all this older stuff, even the "newer" Whecol P50's seem to be lacking in information.
I still have my old maintenance books on the P50, A67/9, Met Vick range of GEB's including the older tall units and the standard NCB GEB's.
Also have an advertising leaflet on the ASF range of HT air breakers, together with a picture of an SF1 OCB.

[alanvickers]

Thanks John - I have modified and added to my earlier message with additional information.

I cannot help with other Reyrolle types of switchgear other than Reyrolle 'F; type. The ones that I saw were non flameproof and I am not now sure what voltages they were used on.

I no longer have my collection of Reyrolle maintenance booklets but I have my early text books, one of which has some Reyrolle photos and possibly some other makes as well. I have a Belmos book that has quite a bit of information in it.

Look forward to the photos.

Alan Vickers.

[John]

I have the Belmos KFG/KFD pamphlet, [ictures of both on it. Basically the same units, just one was vertical and the other horizontal. Worked on both, nice units.
I might have some pictures on Photobucket, I'll check.

[John]

Nothing, I'll upload some from a disk I have files on and post a couple here.
I don't have to use Photobucket for the website, just upload files direct, something one cannot do on forums.

[John]

Here's some equipment. The Baldwin Francis is an SM2, that was the early thyratron E/L protection, BF used before going solid state in the late 1960's. Great gate end boxes!!


A MCU153 by Metropolitan Vickers, later AEI after the takeovers in the mid 1960's.


And an ancient drill transformer, available as standard 50 cycle or high frequency units.

[John]

Here's some more switchgear from way back, some before the 60's, some during the 60's.

M&CS A600 GEB, a very basic piece of gear!!



A pair of HV Circuit breakers, the Met Vick SF! OCB pedestal mount and the AEI ASF air breaker, both were used on the primary of transformers U/G as well as main substation pillar mout HV circuit breakers.


Then the Belmos KFD 3.3KV contactor unit we used as a trunk and gate belt starter.

[John]

The KFG version of the Belmos KFD was the horizontal version, we used those for powering heliminers at Boulby potash mine in North Yorks.
Those in turn derived their power from a Brush flameproof transformer rated at 600KVa, 6.6KV to 3.3KV mounted in a substation, with a transformer mounted Brush SF6 pressurised gas circuit breaker, with the Brush restricted neutral SEL system on the secondary side of the transformer.

[alanvickers]

Thanks John.

The 'ancient drill transformer' I recognise and this we had in its frequency changer form. I called it the MU11 but I might have got this wrong. The MU80/81 were the same height and could be bolted to the drill units. The MU80 and 81 were basically the same except that the MU80 did not have a separate chamber for the busbars and isolator whereas the MU81 did have this. This meant that maintenance of the MU80 could only be carried out after the busbars had been made dead. We generally used these well away from the coal face areas.

I recognise the MetroVick SF1 as it was used at a number of local collieries that had 3,300 volt supplies.

MetroVick seem to have kept the same numbering sequence. The MCU150 was introduced about 1947 for use with the AB Meco Moore cutter loaders. They could be lined up with the MU80/81 and MU11 GEBs. The MCU153, you say was produced in the 1959s and I am presuming from the photo that it wasbuilt to NCB Specifications.

I don't recognise the Belmos KFD unit, my book does not show it as it was produced in about 1962 and covers only medium voltage switchgear.

I have found photos of Reyrolle GA1,GA2 Ga3, and GA8 units also the Belmos NCB Spec. GEBs.

Alan Vickers.

[John]

The drill transformers were the Met Vick MDU32 which was the 50 cycle, and the MU12 which was the 150 cycle unit
The only one I worked on was the MU12 which was used at one of British Gypsums mines, worked perfectly there.

The NCB spec drill unit was the MDU34, which could be and was banked up to the MCU82's and MCU 153's for stable hole/dint and ripping drill supplies.
Wow, they were state of the art when I started my apprenticeship at 16 with the board!
How simple they appear today after working on the Wecol A67's and A69's! Plus a couple of B&F boxes.

[John]

A flameproof air cooled transformer with a type ASF 3.3KV circuit breaker.

[John]

Coal face typical of what I was used to during my apprenticeship. Lighting was only just coming in during the 1960's.