Cutler Hammer, Div of Eaton Corp KD3400 Technical Data

FRED# 296

TD00301003E

MOLDED CASE CIRCUIT BREAKER

APPLICATION ON GROUNDED

B-PHASE SYSTEMS

Occasionally you may have an application that is a delta voltage source with a grounded
“B” phase, also known as corner grounded. Eaton Corporation literature states “for all 3
phase delta grounded B phase applications, refer to Eaton Corporation.” Following are
sketches of what the voltage source looks like with a breaker applied.

Std. 2 Pole Breaker (Fig 1) 2 or 3 Pole breaker with

Unprotected Ground Phase.
Protected
Single
Phase
Load

(Fig 2)

2 Phases
Protected
3 Phase
Load

Std 3 Pole Breaker (Fig 3) Std 3 Pole Breaker (Fig 4)

Protected
Single
Phase
Load

(Use outside poles when 2 poles of a 3 pole breaker are used)

Sizing a breaker for application in a Grounded B-Phase Delta system is different from
sizing a breaker for application in a solidly grounded or low-resistance grounded wye
system because the phase to ground interrupting duty requirement of an individual
breaker pole is different for each case.

A) In a grounded B-Phase System case, a single-line-to-ground fault occurring

downstream of the breaker must be interrupted by a single pole of the breaker
with full line-to-line voltage across that single interrupting pole.

B) In a neutral-grounded wye system, solidly-grounded or low-resistance

grounded; a downstream single-line-to-ground fault must likewise be
interrupted by a single pole of the breaker, but in this case with only line-to­neutral voltage across that single interrupting pole.

This is the difference which determines the values of the following application data table:

Protected
3 Phase
Load

1 6/22/2009

PHASE TO GROUND INTERRUPTING RATINGS

MOLDED CASE CIRCUIT BREAKERS IN GROUNDED B-PHASE SYSTEMS

INTERRUPTION RATING,

CLASSIC

EB 5
EHB 18 10
FB 18 10 8.6
HFB 65 10 8.6
CA, CAH, HCA * 10
JA, KA 25 15 10
HKA 65 15 10
JB, KB, HKB 18 10
LB, LBB, HLB 25 10
DA 25
LA, LAB, HLA 400A 42 15 10
LA, LAB, HLA 600A 30 10 8.6
LC, HLC 30 10 8.6
LCL 65
MA, HMA 42 12 10

MA, HMA W/CERAMIC ARC
CHUTES

MC, HMC 42 12 10
NB, HNB 25 12
NB TRI-PAC 75
NC, HNC 25 12
PB, PC 65 25 20
PB TRI-PAC 100

Series C

GHB, GHC 14
GD 22 8.6

ED, EDH, EDC 10
EHD 14 10
FDB 14 10 10
FD, JD, JDB, KD,LD, LDB, CLD 35 10 10
HFD, HJD, HKD, HLD, CHLD 65 10 10
FDC, JDC, KDC, LDC, CLDC 100 10 10

MDL, CMDL 50 10 10
HMDL, CHMDL 65 10 10
ND, CND 50 14 14
HND, CHND 65 14 14
NDC, CNDC 100 14 14
NDU 150 14 14

240 VAC

42 15 10

kA

480

VAC

600

VAC

2 6/22/2009