GPO exchange power supply

[Vintage_RC]

I recently acquired a Weller TCP iron rated at 45W, 50V. This belonged to a former GPO engineer and had a GPO type plug fitted. I've tested it on 50V dc and it works fine. Was the 50V exchange supply ac or dc?

[Station X]

DC from a battery.

The transformers supplied to enable these irons to be used on a mains supply were obviously AC.

[G6Tanuki]

48V was the standard Telco exchange voltage both here and in the USA.

In times past I installed a bunch of Cisco and Wellfleet routers in Telco local offices that were fitted in 23-inch standard Hubbell racks (with their US spec mounting screws) and they all ran off 48VDC.

[Dave Moll]

A purely resistive heating element is, of course, equally happy with AC or DC.

[Vintage_RC]

Originally Posted by Dave Moll

A purely resistive heating element is, of course, equally happy with AC or DC.

Yes I obviously realise that but the contacts in the Weller TCP will be subject to more sparking erosion with dc.

[Graham G3ZVT]

Both 48 and 50volts are quoted for exchange batteries.

This thread is no exception.

Would I be right in thinking that originally 24 lead-acid accumulator cells were used in series, and the extra 2v was a consequence of them being permanently on float - charge?

Originally Posted by Graham G3ZVT

Both 48 and 50volts are quoted for exchange batteries.

This thread is no exception.

Would I be right in thinking that originally 24 lead-acid accumulator cells were used in series, and the extra 2v was a consequence of them being permanently on float - charge?

Can't answer for the big stuff, but I recall the Corfe Castle exchange around the 50's, was powered by a battery formed by quite large Leclanché cells. The depolariser diameter being around 2.5" and the zinc rod a square section about a half inch to the side. I was delighted to be given the makings of one - I never exhausted it!

[G6Tanuki]

Originally Posted by Graham G3ZVT

Would I be right in thinking that originally 24 lead-acid accumulator cells were used in series, and the extra 2v was a consequence of them being permanently on float - charge?

Certainly in the past large telephone exchanges had a battery room full of lead-acid cells.

The room I remember at an exchange in East London had tiled floors and walls, with semi-open topped black troughs containing the electrodes and acid, all linked up with flat copper bus-bars. Lots of warning signs about explosive gases, and some powerful fans too.