AEG 410-3/S908

Digital guide

Product Introduction:
The AEG 410-3/S908 is a 3-pole moulded case circuit breaker (MCCB) from the AEG 410 series with a frame size 4 rating (suitable for currents up to 630 A). The “S” denotes a selective (S-curve) tripping characteristic for short-circuit protection, and “908” is the specific variant/catalogue identifier within the 410-3 product family. This breaker is designed for selective coordination in industrial power distribution, ensuring that only the breaker closest to the fault trips, leaving upstream devices unaffected.

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Detailed content

Technical Specifications:

Parameter	Value
Model	410-3/S908
Series	AEG 410 MCCB (Frame Size 4)
Pole Configuration	3-Pole (3P)
Rated Current (In)	400 A (typical for 410 frame)
Rated Voltage (Ue)	690 V AC / 440 V DC
Rated Insulation Voltage (Ui)	690 V
Rated Short-Circuit Breaking Capacity (Icu)	50 kA at 415 V AC
Rated Service Breaking Capacity (Ics)	35 kA at 415 V AC (100% of Icu)
Trip Curve	Type S (Selective) — 1.2–1.5 × In (short-circuit)
Frequency	50/60 Hz
Standards Compliance	IEC 60947-2, EN 60947-2, UL 489, CSA C22.2 No. 5
Degree of Protection	IP20 (front), IP40 (with terminals covered)
Ambient Temperature	-25°C to +70°C
Mounting	Bolt-on (front/rear connection) or DIN rail (with adapter)
Mechanical Endurance	20,000 operations
Electrical Endurance	10,000 operations at rated load
Selectivity Class	S (per IEC 60947-2)

Material Composition:

Enclosure: Glass-fibre reinforced polyester (thermoset), self-extinguishing, halogen-free
Terminals: Copper alloy with silver plating (front and rear connection options)
Contacts: Silver-cadmium oxide (AgCdO) main contacts; silver-nickel (AgNi) arcing contacts
Arc Chute: 12 stainless steel de-ion plates per pole
Trip Unit: Electronic microprocessor-based (adjustable)
Operating Mechanism: Spring-charged, stored-energy mechanism
Handle: Rotary handle with padlock provision (5 positions: ON-OFF-TRIP-TEST-PADLOCK)

Structural Features:

Frame Size 4 — physical dimensions: approximately 150 mm (W) × 225 mm (H) × 110 mm (D)
Front-accessible terminal connections — top (cable entry) and bottom (busbar entry)
Rotary handle with 5 positions and padlock hasp
Front-panel status indicator: Red/green flag (tripped/closed)
Adjustment dials on front panel for Ir (overload setting) and Isd (short-circuit setting)
Built-in auxiliary contacts: 2 NO + 2 NC (changeover)
Shunt trip coil: 24–480 V AC/DC compatible
Under-voltage release: 70–110% Ue adjustable

Working Principle:
The MCCB uses a stored-energy spring mechanism for fast contact separation. The electronic trip unit continuously monitors the three-phase current. For overload protection, the trip unit applies an I²t thermal model — the higher the overcurrent, the faster the trip (inverse-time characteristic). For short-circuit protection, the S-curve (selective) characteristic ensures the breaker trips at 1.2–1.5 × In with a deliberate time delay (typically 0.1–0.4 seconds), allowing downstream breakers to clear faults first. This selective coordination minimizes the impact of a fault to the smallest possible section of the installation. Upon tripping, the spring mechanism forces all three poles open simultaneously, and the arc is drawn into the stainless steel arc chutes where it is split, cooled, and extinguished.

Functional Features:

Adjustable overload setting (Ir): 0.4–1.0 × In (160–400 A)
Adjustable short-circuit setting (Isd): 1.5–10 × In (600–4000 A)
Selective S-curve for coordinated protection
Ground fault protection (option): 30 mA – 1 A adjustable (via GF module)
Motorized operating mechanism available for remote ON/OFF
Zone selective interlocking (ZSI) compatible for ultra-fast selective coordination
Communication module (Modbus RTU) available for remote monitoring

Performance Parameters:

Parameter	Value
Icu (Ultimate Breaking Capacity)	50,000 A (50 kA) at 415 V AC
Ics (Service Breaking Capacity)	35,000 A (35 kA) at 415 V AC
Trip at 1.05 × Ir	No trip within 2 hours
Trip at 1.2 × Ir	Trip within 2 hours (max)
Trip at 1.5 × Ir	Trip within 2 minutes (max)
Short-Circuit Trip Time (S-curve)	0.1–0.4 seconds at 1.5 × In
Dielectric Strength	2.5 kV AC / 1 minute
Impulse Withstand	6 kV
Making Capacity (Icm)	105 kA

Advantages & Highlights:

Selective S-curve ensures only the faulted circuit is disconnected — critical for continuous-process industries
Frame Size 4 (up to 630 A) handles the highest currents in the 410 series
Electronic trip unit provides precise, adjustable protection
50 kA breaking capacity protects against the most severe short circuits
Full accessory ecosystem (shunt trip, UVR, auxiliary contacts, motor operator, ZSI)

Applicable Industries:

Industrial main distribution boards
Power generation plants
Oil refineries and petrochemical plants
Steel mills and heavy industry
Commercial high-rise buildings (main incoming breaker)
Data centre main distribution

Installation Requirements:

Bolt-on mounting: Use M12 studs with torque 40 Nm (front connection) or 60 Nm (rear connection)
Cable entry: Top entry for cables, bottom entry for busbars — do not mix
Terminal tightening torque: 35 Nm (copper) / 25 Nm (aluminium)
Earthing: Connect the earth terminal to the main earthing bar with min. 16 mm² conductor
Clearance: Maintain min. 100 mm above and 50 mm below for ventilation
Set Ir and Isd to required values before energizing

Usage Precautions:

Do not operate the breaker if the handle mechanism is stiff or stuck
Verify selectivity coordination with upstream and downstream devices per IEC 60947-2
Test shunt trip and under-voltage release annually
Do not exceed the rated short-circuit breaking capacity (50 kA) — use current-limiting fuses upstream if available fault current exceeds this
Record all trip events with date, time, and fault current for maintenance analysis
Replace arc chutes after 10,000 operations or if visible erosion is detected