It looked very similar to the dummy loads we used at the Telco I worked at for 34 years.... but the telco DL's were used
for load testing emergency generators.....up to 500 kva..( and coils could be switched in /out in parallel with a tap switch, to change the load).
Were those Avtron loads? We used them at Lorain Products to test the telcom power systems! My lab had enough load banks to pull 15,000 amps at -48VDC!
## Nope, these loads were for the 208/120 vac (3 phase) diesel generators that each Central office had. The cell sites (only a few of the bigger cell sites had an emergency generator) ran on 240/120 vac, single phase, like a home. The fan on the portable DL made a hell of a racket. It was towed behind a truck.
## Main office downtown, was 470 / 271 (3 phase).
## we only had small DL's for the +5vdc (@ 40A) supplies. These were DC-DC converters, thousands of them. -52 vdc input..and +5Vdc output.
## Think it was around late 70's, when the change came to the -48 vdc. It was increased to -52 vdc. It's still -52vdc to this day.
## Never did see a huge dummy load for the -52 vdc rectifiers. The -52 vdc rectifiers came in 25-50-100-200-400-800 amp sizes.
Huge things in the 400 + 800 amp sizes. Before I retired in 2009, the new standard was the -52 vdc switching type supplies. 6 x 3.3 kw units in one shelf (20 kw / 400A ccs)...that ran on 208 single phase.... or 240 vac single phase (cell sites). Up to 7-8 shelves in a bay..with a control unit in the middle of the mess. One bay was good for 140-160 kw.
## Main office downtown sucked 3750 Amps @ -52 vdc. We bought the power from the power company at 14.4 kv / 3 phase... then had our own 2000 kva vault transformer ( to step it down to 470/271 vac). The emergency generator on the roof was 1800 kva, and was a V-16 diesel. 2 x 35,000 litre underground ( double walled) diesel tanks below the parking lot. Fuel lines were the size of fire hoses.
## We had a myriad of Lorain products in most offices. Extremely rare we had issues with Lorain equipment.
## On a side note, apparently the large dummy loads can be rented. A buddy had 400 A (240/120) service upgrade to his home. The power company wanted to install a 2nd 50 kva xfmr in parallel with the existing 50 kva xfmr.....and still feed 9 homes. Buddy complained, and they relented, so the new xfmr is just for his home. Now the battle is.... a new, dedicated 50 kva xfmr is only good for 200A, not 400A ! So he's gonna rent a DL, suck 400A CCS, and destroy the new xfmr. Then he will get a 100 kva installed.
## I have '200 A' service into my home... but the 50 kva xfmr is shared with a total of 9 homes. (5.5 kva per home). Power company guys came out..said to just blow it up ( they are over fused with a 9-11 amp slow blow). They said they have em in 25-50-75-100-125 kva sizes ( for mounting on utility poles). They can also be paralleled. Anything bigger, and it has to be mounted on the ground, on a slab, inside a kiosk.
## silly really. My 3-0 cu wire from 200A panel is spliced into 2-0 Al drop line ( it might be 1-0 al). V drop from xfmr to B+ supply is bad news. Once these 100% electric cars become more mainstream, the pole pig xfmrs will start popping offline, massive upgrade required.
sri for the diatribe.
Jim VE7RF
