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EntelliGuard R Circuit Breaker Retrofill AKD-6 Installation Manual DEH-41548 07/15
History and Types
AKD
AK—Power Circuit Breaker Equipment
D—Drawout circuit breaker construction
Manufactured from 1951 to 1975 were these: all bolted, copper bus design, all drawout breakers—AK-1, —2, —3,—
15 / 25 / 50 / 75 / 100; the 4000A-max bus rating. Back then, breakers had a ratcheting drawout mechanism, with
an open-door drawout. Breakers were painted ANSI 61, light gray, manufactured in Philadelphia from 1951 to the
mid-60s and in Burlington, Iowa from the mid-60s to 1975.
The breaker compartment was a welded assembly, and the equipment frame was bolted. Breaker boxes were
stacked to make a vertical section with equipment frame around the breaker boxes. There were no bus
compartment barriers, just an open bus design. Ring silver-plating was applied to bolted connections.
AKD-5—AK25/AK50
Manufactured from 1960 until 1977, the aluminum bus had copper that was “flash-butt welded” to the aluminum
at bolted connections. During that time, AK-2A, 3A -25 / 50 / T50 / 75 / 100 (“A” signifies AKD-5 drawout) were
produced. Breakers up to 2000A had primary finger clusters. 3000 & 4000A breakers had a circular primary finger
cluster arrangement in the switchgear compartment. Pull-lanyard drawout mechanism on early design was
replaced by a single jackscrew mechanism and then later replaced by a double jack-screw mechanism. Featured
is a closed-door, drawout with inner house breaker compartment. Two bus levels are available with a ring bus
used at 4000A. Particulars include: welded/riveted frame, bus compartment barriers, line/load separation barriers
on mains and ties, isolation barriers on transformer transitions, copper runbacks on feeder breakers, ring silver-
plating on copper, and aluminum bus un-plated (welded connections). The switchgear is painted sand-gray (beige),
with some instrument doors painted blue. AKR-30/50 in 22"-wide sections were introduced in AKD-5 construction,
early 70s. AK25s and AK50s were also available as substructure kits for OEMs to build around customer gear.
Note: All legacy AK & AKR breakers have a draw out letter code “A”. Entelliguard R retrofill breaker for this gear will
have a catalog number beginning with R1 for AK replacements or R2 for AKR-30/50 replacements.
AKD-6—AKR30H/AKR30L/AKR50H/AKRT50H
The AKD-6 was manufactured in Salisbury, NC from 1977 to 1981. Some AKD-5s, which were built in Salisbury from
1975 until 1977, got name-plated as AKD-6. There is no “flash-butt” welded aluminum to copper. Aluminum bus is
tin-plated and bolted at shipping splits (but welded everywhere else). Copper bus design has ring silver plating at
bolted joints. AKR-75 / 100s were introduced during this time. Stab-and-finger connections on 3200A and 4000A
breakers were improvements, versus the round the primary disconnects located on the AKD-5s.
The AKD-6 uses inner-house drawout breaker compartments on the 800—2000A breaker compartments. They are
painted ANSI 61 light gray and breakers have ECS or SST trip units.
AKD-6 should mark a shift away from all AK breakers and to AKR breakers. The AKR-30/50/50H/T50 breakers used
in AKD6 have a shallow 1” steel front escutcheon are drawout letter code “A” i.e. AKR-4A-30 and will be replaced by
an EntelliGuard R with a catalog number beginning with
R2
. The AKR-30/50/50H/T50 breakers sold to OEMs for
their switchgear have a 5” deep plastic front escutcheon & spring loaded sliding “picture frame”. These are draw
out letter code “B” i.e. AKR-4B-30 which will be replaced by an EntelliGuard R with a catalog # beginning with
R5
.
AKD-8—AKR30H/AKR30L/AKR50H/AKRT50H
The AKD-8 was manufactured in Salisbury, NC from 1980 to 1984 and in Burlington, Iowa from 1984 to 1999. It
was mostly replaced by AKD-10 in 1999 to 2000 but was available thru 2015. Model 1 and 2 have extruded
