3SM8N, MCCBs with thermal magnetic trip units

Independent power supply with build-in power source,directly draws power from the incoming end to avoid the risk of protection function failure caused by external power supply failure.

● Overload protection
● Short circuit protection
● Isolation
● Controlling
● Used in residential building, non-residential building, industry, energy and infrastructure


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Overview

Overview

3SM8N.1

Applications and functions

● Incoming and outgoing function in distribution systems

● Switching and protection devices for motors, transformers and capacitors

● Disconnect or units with features for stopping and switching off in emergency mechanisms and terminal covers in conjunction with likeable rotary operating

● Available in the following versions

● Power protection: the overload and short-circuit releases are designed for the protection of cables, leads and non-motor loads

● Motor protection: the overload and short-circuit releases are designed for optimized protection and direct-on-line starting of induction squirrel-cage motors. The circuit breakers for motor protection are susceptible to phase failure and feature an adjustable trip class

Instruction of type code

3SM8N.2

● There is no frame E and F for motor protection.

● Only M type (medium breaking capacity type) has 4 poles:

a. 4A: N-pole fixed without over-current release unit, it has been connected all along, and does not act with other three poles to turn on or off.

b. 4B: N-pole fixed without over-current release unit, it acts with other three poles.

c. 4C: N-pole fixed with over-current release unit, it acts with other three poles.

d. 4D: N-pole fixed with over-current release unit, it has been connected all along, and does not act with other three poles to turn on or off.

Instruction of external structure

Technical Specifications

Selection and ordering data

Accessories

Tripping Characteristic

For power distribution

No.	Test current	I/In	Conventional time	Start status
1	Conventional non-trip current	1.05	2h (In > 63 A), 1h (In ≤ 63 A)	Cold status
2	Conventional trip current	1.3	2h (In > 63 A), 1h (In ≤ 63 A)	Right after test No.1

For motor protection

No.	Operational current	Conventional time	Start status	Remark
1	1.0 In	2 h	Cold status	-
2	1.2 In	≤ 2 h	Right after test No.1	-
3	1.5 In	≤ 4 min ≤ 8 min	Cold status Cold status	10 ≤ In ≤ 225 225 ≤ In ≤ 630
4	7.2 In	4 s ≤ T ≤ 0 s 6 s ≤ T≤ 20 s	Cold status Cold status	10 ≤ In ≤ 225 225 ≤ In ≤ 635