Hi Gents, sorry for any truncated replies as I was having problems with my new password.


Standard textbooks from the 30's relate to 6 phase (with/without reactor( for large plating plants and possibly some drives applications. The more advanced work will analyse the systems and show low PF issues, but I think this was just considered a cost penalty.

We do have a static machine set up as a phase advancer in the Discovery Museum, but no details of what it operated with.

The growth of TV's as has been pointed out. would, with the advent of AC/DC (transformerless) sets from the early 50's cause poorer power factors with the 1/2 wave rectification being used in place of the full wave of transformer fed sets.

This was made worse with the advent of colour sets that had regulated power supplies driven by 1/2 wave ,phase angle fired SCRs. It was noted in some of the trade press that this was not a good thing.

At this time there was also the advent of phase angle light dimmers!!!

Total of all these loads was probably only a small proportion of the full connected load.

Again it was considered a cost penalty and cables were well rated, so not too much of a problem. There may be some references in guidance notes issued by local boards to large industrial users, but I have not seen any; certainly as has been pointed out there was nothing in the then current regs.

On a slightly different angle, the effect was well known as by the 60's I think fluorescent light units were fitted with PFI caps.


There was an incident in the 70's at a local factory where a 1MVA 11Kv/440 transformer blew up .

It fed a spot welding shop where the labour force was keen to prolong jobs, and thought that by setting the cycles control on the spot welder to max, then adjusting the phase angle control to give a satisfactory weld they would have an easier time! The computed PF after the accident was pretty poor and the triplen effects were large.


From memory the regs started to come in in the 80's when a whole sheaf of EEC rules started to appear that related to EMC.

The climax of this appeared in Airbus Electrical directives for A400M in the 2000's. Not only were the alternators frequency wild(380 to 620Hz), but emc/ power quality standards demanded 18 phase rectification to feed the PFI correction circuits of the various electronic PSU's being designed.

It was an interesting time.


Ed

Hi Gents, sorry for any truncated replies as I was having problems with my new password.


Standard textbooks from the 30's relate to 6 phase (with/without reactor( for large plating plants and possibly some drives applications. The more advanced work will analyse the systems and show low PF issues, but I think this was just considered a cost penalty.

We do have a static machine set up as a phase advancer in the Discovery Museum, but no details of what it operated with.

The growth of TV's as has been pointed out. would, with the advent of AC/DC (transformerless) sets from the early 50's cause poorer power factors with the 1/2 wave rectification being used in place of the full wave of transformer fed sets.

This was made worse with the advent of colour sets that had regulated power supplies driven by 1/2 wave ,phase angle fired SCRs. It was noted in some of the trade press that this was not a good thing.

At this time there was also the advent of phase angle light dimmers!!!

Total of all these loads was probably only a small proportion of the full connected load.

Again it was considered a cost penalty and cables were well rated, so not too much of a problem. There may be some references in guidance notes issued by local boards to large industrial users, but I have not seen any; certainly as has been pointed out there was nothing in the then current regs.

On a slightly different angle, the effect was well known as by the 60's I think fluorescent light units were fitted with PFI caps.


There was an incident in the 70's at a local factory where a 1MVA 11Kv/440 transformer blew up .

It fed a spot welding shop where the labour force was keen to prolong jobs, and thought that by setting the cycles control on the spot welder to max, then adjusting the phase angle control to give a satisfactory weld they would have an easier time! The computed PF after the accident was pretty poor and the triplen effects were large.


From memory the regs started to come in in the 80's when a whole sheaf of EEC rules started to appear that related to EMC.

The climax of this appeared in Airbus Electrical directives for A400M in the 2000's. Not only were the alternators frequency wild(380 to 620Hz), but emc/ power quality standards demanded 18 phase rectification to feed the PFI correction circuits of the various electronic PSU's being designed.

It was an interesting time.


Ed