Mitsubishi NF-S Series User Manual

9
Table 3.1 Comparison of Thermal-Magnetic, Hydraulic-Magnetic and Electronic Types
Item
Ambient
temperature
Frequency
Mounting
attitude
Flexibility
of operating
characteristics
Flexibility of
rated current
Thermal-magnetic type
Operating current is affected by ambient
temperature (bimetal responds to absolute
temperature not temperature rise).
Negligible effect up to several hundred Hz;
above that the instantaneous trip is affec-
ted due to increased iron losses.
Negligible effect.
Bimetal must provide adequate deflection
force and desired temperature characteris-
tic. Operating time range is limited.
Units for small rated currents are physically
impractical.
Hydraulic-magnetic type
Affected only to the extent that the damp-
ing-oil viscosity is affected.
Trip current increases with frequency, due
to increased iron losses.
Mounting attitude changes the effective
weight of the magnetic core.
Oil viscosity, cylinder, core and spring de-
sign, etc., allow a wide choice of operating
times.
Coil winding can easily be designed to suit
any ampere rating.
Negligible effect up to 630A;
Above that operating current decreases
due to increase of a fever.
IF distortion is big, minimum operating cur-
rent increases.
Distorted
wave
Electronic type
Within the range of 50(60)~100% of rated
current, any ampere rating are practical.
Also, to lower the value of short-time delay
or instantaneous trip can be easily done
comparatively.
Operating time can be easily shortened.
To lengthen operating time is not.
Negligible effect
Tripping current of some types decrease
due to CT or condition of operating circuit
with high frequency, and others increase.
Negligible effect
For peak value detection, operating current
drops.
Operating time
Current
Operating time
Current
Operating time
Ceiling
Horizontal
ON
ON OFF
OFF
Current
Operating time
Current
Operating time
High frequency
Low frequency
Current
Operating time
High frequency
Low frequency
Current
Operating time
High temperature
Low temperature
Current
Operating time
High temperature
Standard temperature
Low temperature
Current
Operating time
Current
Operating time
Current
Operating time
Current
Above 700A
Operating time
Current
Small current width
Current width
Operating time
Current
Peak value
detection
Operating time
Current
Operating time
Current

Mitsubishi NF-S Series Specifications

General

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