Earthing neutral and frequency of 40 Kw generator.

That would depend on the studio. TC1 had an installed load of half a megawatt! But all phases came from the same source and would be in sync. The only time Problems arose was when there were attempts to run the studios on 525/60. Although there was 60Hz generator for the technical equipment, nobody thought about the lighting and there was a 10Hz beat on the pictures.

Rolling hum bars tended to occur on domestic tv sets, We never saw them in the studios. The camera/monitor would have been sent for repair.

The coloured lag was due to the different tubes in the camera having different lag characterists. Remember, each camera would have 4 videcon tubes

Reply to
charles
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I'm pretty certain all the outlets on the lighting barrels (ie the most commonly used) were on the same phase. Floor lighting outlets on a different one.

Of course other studios would use a different phase as the 'main' one. To balance things up as much as practical.

I'll have to dig up my old Evesham notes. Such things were covered on the STO course.

Reply to
Dave Plowman (News)

It could cause the output from that winding to fall, or yo fail altogether. As to tripping - much depends on the type of circuit breaker and what its actually protecting.

Better quality armature windings will be made like that in the first place - it keeps dust and abrasive dust out of the windings, and reduces and vibration in them.

Reply to
John Rumm

An aviation museum perhaps? Widely used in aircraft.

Andy

Reply to
Vir Campestris

I was thinking that. I am going to Cosford soon to see if I can get a bette r understanding of the compressor problem in Jets. I have no idea if they w ould be interested in anything like that. Come to think of it the one unfin ished product locally; a Spitfire in the Stoke Pottery museum, qualifies it as an aircraft museum.

What can the OP tell us about the kit?

Reply to
Weatherlawyer

To indicate speed difference, tungsten only need do a few Hz, which it does easily.

Household 60w lamps can put out light at audio frequencies, albeit heavily attentuated, and were occasionally used for that by hobbyists. Such lamps a re different to 650w/1kW theatre lamps, the latter having far thicker filam ents and thus much longer time constants.

NT

Reply to
tabbypurr

You've still lost me. Do you mean the sound to light sort of thing?

Reply to
Dave Plowman (News)

I was addressing the issue of using neons in place of incandescent lamps to determine synchronisation between two generators (in this case, every generator connected to the national grid and your lister driven 3 phase genset).

As I understand it, you're not trying to parallel up your 3 phase genset to the public mains supply, just using a single phase incandescent lamp synchroscope to use the mains frequency as a reference by which to set the speed of your 3 phase genset the use of which now seems to be causing the earth leakage breaker to trip.

I suspect that the mistake you've made is to plug into a 13A wall socket that's protected by an ELCB or equivilent to access the mains supply as your frequency reference.

If, otoh, the consumer unit is protected by a whole house ELCB, then your simple incandescent lamps synchroscope just isn't "Going to 'cut it'" and, contrary to good sense, your cheapest option may prove to be tabbypurr's suggested use of neon lamps (but only because you're not going to be relying on it to *actually* parallel up *one* of the three phases of your genset to the mains supply, merely use it to ascertain when your genset is frequency, but not phase, matched to the mains supply).

Incidentally, I'd crossbond the genset frame to your local earth point and, for good measure, crossbond the genset's neutral to your consumer unit's incoming neutral. Protection against 'earthing faults' demands such crossbonding of the neutrals and (frame) 'earths in order to function properly (fuses and elcbs).

Good luck % HTH

Reply to
Johnny B Good

As I understand the OP, George isn't trying to synch up to the mains, just use the mains frequency as a reference by which to set the speed of his 3 phase genset. I suspect his incandescent lamps 'synchroscope' is being fed via an elcb protected supply (13A socket in his workshop). Normally, the uneconomic consumption of such a lamps based synchroscope is not an issue but, in this particular (peculiar?) case, it's now creating an elcb issue.

If he doesn't care for tabbypurr's idea of using neon lamps, he could use a one to one isolating transformer between his synchroscope box and the 13A mains socket so that the 'neutral' connection of the secondary winding is to the genset's neutral instead of the consumer unit's neutral. The potential 180 degree phase reversal won't be an issue when the synchroscope is being used simply to match frequency (however, the transformer secondary could be wired for phase coherence if phase matching is required - in this instance it isn't).

As a matter of fact, there are plenty of alternative ways by which to compare two different source frequencies, it's just a pity that George's tried and trusted incandescent lamps based synchroscope method is incompatable with ELBS. :-)

Reply to
Johnny B Good

Then you've totally misunderstood the principle by which such incandescent lamps synchroscopes work. In effect, you're using the lamps as voltage amplitude detectors where brightness depends on the square law of ac voltage (power function of the product of voltage and current in a purely resistive load).

It's not the 100 brightness peaks a second we're looking at, it's the voltage difference between phases from two different supplies that have their neutrals bonded together. This voltage difference is amplitude modulated by the frequency *difference* between the two supply sources and it is *this* 'beat effect' on the lamps' brightness that's being observed.

Reply to
Johnny B Good

Not very well, and not to a very good depth of modulation (3 or 4 percent at 2KHz or so with a DC biassed torch bulb istr).

Reply to
Johnny B Good

Ah. An explanation I understand at last. Thanks. I was thinking more of a strobe function.

Reply to
Dave Plowman (News)

See what I meant by "various ways" to set the speed of that Lister powered genset? :-)

Reply to
Johnny B Good

Neons won't get you in sync, but they will compare the frequencies without tripping anything. Filaments have much more brightness change around peak voltage, so are good to sync, but also trip RCDs.

NT

Reply to
tabbypurr

The usual voltage ELCBs usually don't care about a lightbulb's worth of earth leakge. RCDs do, sometimes aka current ELCBs. Nothing cares about neons.

NT

Reply to
tabbypurr

Response depends on rated filament current. Pick high voltage low current for best response.

NT

Reply to
tabbypurr

Nor did it seem surprising to me after re-reading the OP after responding to tabbypurr's suggestion of using neon lamps in a synchroscope (not a good idea if you plan to rely on it to determine the point at which to get the "*least* bang for your buck" when you close the breaker. :-).

However, purely from a frequency comparison point, a perfectly acceptable alternative in this situation (provided you don't forget why neon lamps aren't suited to the task of synchronising phases to within a few degrees of each other and misuse it for this function).

Not just likely, it had *damn well better be* cross-bonded to the incoming supply's neutral (and earth) or else it won't be safe against framing faults!

Reply to
Johnny B Good

If the OP has a RCD, then the neutrals should be bonded after they have passed their respective RCDs, so that any current in the live phase is matched in the neutral conductor.

I do agree the use of neons with their very low current draw should be ideal in determining frequency errors.

Reply to
Fredxxx

In a sense, neons are like 'stupidity', not a problem in small quantities but a major force to be reckoned with in very large numbers as most politicians are only too well aware. :-)

BTW, thanks for the heads up on ELCBs and RCDs. I can never remember the differences between what would seem, on the face of it, to be devices with essentially the same function. We don't have a single one of either of those devices in this house, hence my lack of motivation to learn the distinction between them. :-)

Reply to
Johnny B Good

The cannibalised battery powered transistor radio and 3v torch was the favoured combination for the transmitter (along with an ORP12(?) 'photocell' and another transistor amplifier (or even the same cannibalised transistor radio in a switched simplex setup) for the receiver) amongst the usual age range of 'electronics experimenters', usually juvenile 'Nerds'. Battery operation kept such experiments 'safe' in the hands of such child prodigies.

Also, the small compact filament is what gave the 3 volt torch its relatively 'tight beam' with a modestly sized reflector. The choice was between a long bulb life and really muffled audio or between short life with less muffled audio by over-volting the torch bulb by adding a third cell in series with the two cell battery pack (essentially a pair of C cells in a cardboard tube) sometimes a couple of partially exhausted 3 volt batteries would be used (then, as now, battery power wasn't cheap).

Reply to
Johnny B Good

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