Constant Current Load

[Electric-Light]

There's a good ground available at each end.....
And SWER works on non-trivial runs such as the Pacific Intertie.

SWER is not normally used in the The Dalles, OR <-> Sylmar, CA link. It is a +/- 500kV bipolar system operating at 1MV. During normal operations, the current is carried between conductors. If one of the conductors are downed for some reason, it can operate in monopolar mode at reduced capacity using the ground as the return path, but because its a DC, there is such thing as galvanic corrosion concerns for pipelines and metal structures nearby.

 

[Open Neutral]

SWER is not normally used in the The Dalles, OR <-> Sylmar, CA link.

My memory is hazy, but ISTM the Pacific Intertie was SWER, or SW_O_R; at one point in its history. There's a large ocean ground array off ?Santa Monica? I think. Wonder what it does to the fishing?

Of course, the Intertie has been rebuilt several times; ITSM the south end station has been badly damaged at least twice in earthquakes. So maybe it is no longer or....

 

[PetrosA]

The guy who taught me residential work was an electrician in Viet Nam and had lots of stories about trying to find the burnt bulbs on the airstrip they maintained. I can't even imagine doing that kind of work while the airstrip was being shelled. Those stories actually made wiring up latrines sound like fun

 

[gar]

110330-1015 EDT

There has now been considerable discussion on airfield lighting. It should be noted this is not a constant current load, nor a resistive load. It is in between these. The airfield application illustrates a constant current source application, but not a very constant current load.

Whereas a current loop sensor device is very much a very good constant current load at a given input signal level. This is achieved thru feedback circuits.

A bipolar junction transistor is a fairly constant current load within certain ranges without feedback. For example by experiment with a single sample of a 2N4400 the collector current was 4.72 MA at 5 V and 5.04 MA at 25 V with a constant base current.

A standard 100 W tungsten incandescent produced the following results:

V I Calculated I for a resistance of 141.176 ohms
005 .. 0.16 .. 0.04
010 .. 0.23 .. 0.07
020 .. 0.32 .. 0.14
040 .. 0.45 .. 0.28
060 .. 0.57 .. 0.43
080 .. 0.68 .. 0.57
100 .. 0.77 .. 0.71
120 .. 0.85 .. 0.85

The 100 W bulb is not a very constant current load.

.