Mitsubishi NF-S Series User Manual

13
4.6 Switching Characteristics
The MCCB, specifically designed for protective inter-
ruption rather than switching, and requiring high-con-
tact pressure and efficient arc-extinguishing capabil-
ity, is expected to demonstrate inferior capability to
that of a magnetic switch in terms of the number of
operations per minute and operation life span. The
specifications given in Table 4.3 are applicable where
the MCCB is used as a switch for making and break-
ing rated current.
Electrical tripping endurance in MCCBs with shunt
or undervoltage tripping devices is specified as 10%
of the mechanical-endurance number of operations
quoted in IEC standards.
Shunt tripping or undervoltage tripping devices are
intended as an emergency trip provision and should
not be used for normal circuit-interruption purposes.
4.7 Dielectric Strength
In addition to the requirements of the various interna-
tional standards, Mitsubishi MCCBs also have the
impulse-voltage withstand capabilities given below
(Table 4.4). The impulse voltage is defined as sub-
Table 4.3 MCCB Switching Endurance
Frame size
100 or less
225
400, 630
800
1000~2000
2500, 3000
3200, 4000
Operations per hour
120
120
60
20
20
10
10
Number of operations
Without current
8500
7000
4000
2500
2500
1500
1500
With current
1500
1000
1000
500
500
500
500
Total
10000
8000
5000
3000
3000
2000
2000
stantially square-wave, with a crest length of
0.5~1.5µsec and a tail-length of 32~48µsec. The volt-
age is applied between line and load terminals (MCCB
off), and between live parts and ground (MCCB on).
Table 4.4 MCCB Impulse Withstand Voltage (Uimp)
Line
Type
Impulse-voltage (kA)
MB
NF
S
C
U
MB30-SP MB50-CP MB50-SP
MB100-SP MB225-SP
NF30-CS
NF400-CP NF630-CP NF800-CEP
NF50-CP NF60-CP NF100-CP NF250-CP
NF100-RP NF100-UP NF225-RP NF225-UP
NF400-SP NF400-SEP NF400-HEP NF400-REP NF630-SP NF630-SEP
NF630-HEP NF630-REP NF800-SEP NF800-HEP NF800-REP
NF800-REP NF1000-SS NF1250-SS NF1600-SS
MB30-CS
4
6
6
8
6
6
4
8
8
NF30-SP NF50-HP NF60-HP
NF50-HRP NF100-SP NF100-HP NF100-SEP NF100-HEP
NF160-SP NF160-HP NF250-SP NF250-HP NF250-SEP NF250-HEP
NF400-UEP NF630-UEP NF800-UEP

Mitsubishi NF-S Series Specifications

General

Brand	Mitsubishi
Model	NF-S Series
Category	Circuit breakers
Language	English