Distances Between Circuit Breaker And Earthed Metal Parts - Mitsubishi Electric C Series Handling And Maintenance

3.6.5 Distances between circuit breaker and earthed metal parts

When short circuit current is cut off, ionized gas goes out of the exhaust port at the power source side
of the circuit breaker. At the power source side of the circuit breaker, provide the insulation distance
shown in the table so that the outgoing gas may not be bothered. Short circuit and ground fault can
also be resulted by dropped metal pieces, abnormal surge voltage generated in the lines, or by dust,
iron chip, and salt content. Insulate uncovered conductors at the power source side of the circuit
breaker exactly using insulation barriers, insulation tubes, and tapes.
Note:Vertical distance differs by each type of the lower circuit breaker.
A : Distance from circuit breaker to ceiling plate
B1 : Distance from lower circuit breaker to unco-
vered conducting part of the terminal of upper
circuit breaker (front connection)
B2 : Distance from lower circuit breaker to the end
Insulation distance mm (AC 440V and less)
Distances are obtained tests defined in the IEC 60947-2 standard.
NFB
Series
Type name
NF30-CS, MB30-CS
NF32-SW, NF63-CW, MB30-SW, MB50-CW
NF63-SW, NF63-HW, MB50-SW
NF125-CW
NF125-SW, MB100-SW
NF125-HW
NF250-CW
NF160-SW, NF250-SW, MB225-SW
NF160-HW, NF250-HW
C
NF125-SGW, NF125-HGW, NF160-SGW
·
NF160-HGW, NF250-SGW, NF250-HGW
S
NF400-CW
·
NF400-SW, NF400-SEW
MB
NF400-HEW, REW
NF630-SW, NF630-SEW, NF630-CW
NF630-HEW, REW
NF800-SEW, NF800-CEW
NF800-HEP, REP
NF1000-SEW, NF1250-SEW, NF1250-SDW,
NF1600-SEW, NF1600-SDW, NF2000-S,
NF2500-S, NF3200-S, NF4000-S
NF125-RGW, NF125-UGW
NF250-RGW, NF250-UGW
—
—
U
NF400-UEW
NF800-UEW
NF1250-UR
BH BH, BH-P, BH-S, BH-PS
NF50-SWU (AC240V and less)
NF100-CWU (AC240V and less)
NF100-SWU (AC480Y/277V and less)
UL
NF225-CWU (AC240V and less)
NF-SFW, NF-SJW (AC600Y/480V and less)
NF-HJW (AC600Y/480V and less)
Note 1. The figures in parentheses in the table are the dimensions applied to AC 230 V and
lower.
Note 2. Settle D2 dimension so that insulation distance (a according to each standard) can
be secured.
Note 3. When NVs at both sides are put in contact and 2500A or higher current flows through
NV at one side, the other NV may operate needless motion being affected by the
magnetic field. In such a case, set D2 at 50mm or more.
23
Ceiling plate Ceiling plate Ceiling plate
(Direct connection (Connection with (Bar connection)
of wire) ring-type terminals)
face of upper circuit breaker (rear connection)
C : Insulated length of power source terminal of
circuit breaker (front connection)
D1 : Distance from a side of breaker to side plate
D2 : Side to side spacing of breakers
a : Clearance specified in standard
NV30-CS, NV50-CSA
NV63-CW
NV32-SW, NV63-SW, NV63-HW
NV125-CW
NV125-SW
NV100-HEP, NV125-HW
NV250-CW
NV250-SW, NV250-SEW
NF250-HW, NV250-HEW
NV400-CW
NV400-SW, NV400-SEW
NV400-HEW, REW
NV630-CW, NV630-SW, NV630-SEW
NV630-HEW
NV800-SEW
NV800-HEW
NV1000-SB, NV1200-SB
NV125-RW
NV250-RW
NV50-SWU (AC240V and less)
NV100-SWU (AC240V and less)
NV225-CWU (AC240V and less)
Ceiling plate
D2
(Rear connection)
a
NV
Uncovered
Type name metal plate
Without
terminal
cover
10
5
10
50 (30)
50 (10)
50
40
70 (40)
80
— 30
60
70
200
70
200
80
200
100
—
—
(Note 4)
— 70
— 80
—
200
—
10
10
— 50 (30)
50 (10)
40
— 30
— 30
Note 4. The terminal unit at the power side has no exhaust port and is so composed to
discharge no arc requiring no insulation distance (space) to the power side. When
an earth metal is put in contact with the terminal unit, however, uncovered part of
the terminal or the wire must be insulated exactly using terminal covers, insulation
barriers, tubes, and tapes to secure insulation distance (space) to the earth metal
(the distance specified in board specifications etc.).
Note 5. Where surface type uncovered bars are used for connection, insulate by taping to
the point where the bars overlap with the insulation barrier or to the root of the
circuit breaker.
Note 6. In case of over AC440V, the distance is 10mm.
Insulation barrier
(Insulation tube or tape will do)
Side plate
D1
D2
In case of
NF400-CW NV400-CW
NF400-SW NV400-SW
NF400-SEW NV400-SEW
NF400-HEW NV400-HEW
NF400-REW NV400-REW
NF1600-SEW
NF1600-SDW
Ceiling plate Vertical spacing
B1, B2
A
Insu- With-
With
lated out
termi-
plate, termi-
nal
With
coated nal
terminal
cover
plate cover
cover
10 10 20 20
5 5 20 20
10 10 30 30
40 (30) 10 50 50
30 (10) 10 50 50
40 40 80 80
40 40 50 50
40 40 70 (50) 50
60 60 80 80
30 30 50 50
60 60 60 60
70 70 70 70
200 200 200 200
70 70 70 70
200 200 200 200
80 80 80 80
200 200 200 200
100 100 100 100
0 0 0
(Note 4) (Note 4)
70 70 70 70
80 80 80 80
200 200 200 200
10 10 20 20
– 10 30 30
– 10 50 50
– 10 50 50
– 40 50 50
– 30 50 50
– 30 50 50
Horizontal spacing
C D1 D2
20
20
25
25
25
40
50
50
60
5
(Note 2)
40
70 (Note 3)
150
70
150
80
150
100
5
25
70
(Note2)(Note3)
80
200
20
25
25
25
50
5 (Note 6)
5 (Note 6)