Wattage of large 4-terminal 0.01 ohm resistor, want to know

[L Chung]

Hi,

I have bought a high wattage 4-terminal Dale resistor from eBay. I
could not determine the wattage from the markings on the body and no
luck from the Vishey Dale website either.

Its gold in color, made of two rectangular flat aluminium blocks
bolted together by 10 countersink screws, with 8 holes for mounting
onto a heatsink. Dimensions of the body are WxHxD=8"x2"x1".

Current connection is at either ends(C) and two wires(P) exit near
each end.

The date code 7339 probably refers to year 1973 and week 39th.

Does anyone knows the rated wattage of such resistor when fitted on a
heatsink?

DALE, SPR-390-3, 0.01ohm, 1%, 7339.

Note: o:hole, +:screww

-------------------------------------------------
|o + o + o + o|
C |+ +| C
===| @ @ |====
|+ \ / +|
|o | + o + o + | o|
-----|-------------------------------------|-----
| |
|P |P


Thanks

L.Chung

 

[Winfield Hill]

L Chung wrote...

I have bought a high wattage 4-terminal Dale resistor from eBay. I
could not determine the wattage from the markings on the body and no
luck from the Vishey Dale website either.

Its gold in color, made of two rectangular flat aluminium blocks
bolted together by 10 countersink screws, with 8 holes for mounting
onto a heatsink. Dimensions of the body are WxHxD=8"x2"x1".

Current connection is at either ends(C) and two wires(P) exit near
each end.

The date code 7339 probably refers to year 1973 and week 39th.

Does anyone knows the rated wattage of such resistor when fitted on a
heatsink?

DALE, SPR-390-3, 0.01ohm, 1%, 7339.

Note: o:hole, +:screww

-------------------------------------------------
|o + o + o + o|
C |+ +| C
===| @ @ |====
|+ \ / +|
|o | + o + o + | o|
-----|-------------------------------------|-----
| |
|P |P

As you noted, Dale is now Vishay. They still make the SPR-2213 and
SPR-2214, which appear to be similar but smaller. The '2214 version
is 4.5" long and is rated at 50W, or 100W when on a heat sink.
http://www.vishay.com/docs/30224/spr.pdf


Thanks,
- Win

whill_at_picovolt-dot-com (use hill_at_rowland-dot-org for now)

 

[R.Legg]

Its gold in color, made of two rectangular flat aluminium blocks
bolted together by 10 countersink screws, with 8 holes for mounting
onto a heatsink. Dimensions of the body are WxHxD=8"x2"x1".

Current connection is at either ends(C) and two wires(P) exit near
each end.

The date code 7339 probably refers to year 1973 and week 39th.

Does anyone knows the rated wattage of such resistor when fitted on a
heatsink?

DALE, SPR-390-3, 0.01ohm, 1%, 7339.

SPR indicates special-purpose wirewound. The parts are derated to 0W
at 275DegC.

Dale metal-clad parts are typically rated at 25W per linear inch of
resistor body length with 1"width heatsink interface, and 50W/linear
inch with a 2"width heatsink interface. At 8"x2" your part will be
book-labelled in the region of 400W.

SPR part numbers do not normally indicate a wattage rating.

RL

 

[legg]

As you noted, Dale is now Vishay. They still make the SPR-2213 and
SPR-2214, which appear to be similar but smaller. The '2214 version
is 4.5" long and is rated at 50W, or 100W when on a heat sink.
http://www.vishay.com/docs/30224/spr.pdf

SPR prefixes were used for a wide variety of special power resistor
styles and configurations. It was a wild-card prefix, denoting
products that were not currently in high-volume production, and
required a special order.

For example, the SPR-1002 is an NH250 with a central pipe intended to
allow water cooling and SPR-2093 is a through-hole-solderable
4-terminal solid-wire shunt.

Ceramic resistors are probably different beasts altogether.
SPR-2213/4 are SPR because of optional constructions offered - with
added terminals, more rugged element materials construction and
winding styles.

Metal-clad parts use a silicone filler and have welded element
terminations. The larger clad parts are derated to 40% or less in free
air, without the heatsink. There may also be restrictions for the part
number that do not follow the general clad case, given it's apparent
high-current shunt function.

RL

 

[L Chung]

Dale metal-clad parts are typically rated at 25W per linear inch of
resistor body length with 1"width heatsink interface, and 50W/linear
inch with a 2"width heatsink interface. At 8"x2" your part will be
book-labelled in the region of 400W.

400W! That's huge. I guess this type of resistors fill the needs where
a common current shunt can't because open current shunts do not have
heatsinking and so must not gets too hot. Below 20W for most?

Thanks all for the valuable information.

L.Chung