Mitsubishi NF800-CEP User Manual

ADVANCED AND EVER ADVANCING
MOULDED CASE CIRCUIT BREAKERS
TECHNICAL NOTES
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Mitsubishi NF800-CEP Specifications

General

Brand	Mitsubishi
Model	NF800-CEP
Category	Circuit breakers
Language	English

Summary

2. FEATURES – Advanced MCCB Design Technology & Performance

2.1 Arc-Extinguishing Device – ISTAC

Details ISTAC technology for improved current-limiting and breaking performance.

2.2 Digital ETR (Electronic Trip Relay)

Explains the digital ETR for fine protection using microcomputer and custom-IC.

4. CHARACTERISTICS AND PERFORMANCE

4.1 Overcurrent-Trip Characteristics (Delay)

Details tripping times for overcurrents at different percentages of rated current.

4.2 Short-Circuit Trip Characteristics (Instantaneous)

Discusses instantaneous trip settings and their importance for coordination.

5. CIRCUIT BREAKER SELECTION

Circuit Breaker Selection Table Overview

Selection Tables by Voltage and Type

Provides detailed selection tables for 230VAC and 440VAC MCCBs.

6. PROTECTIVE CO-ORDINATION

6.2 Interrupting Capacity Consideration

Discusses capacity consideration for MCCB selection based on voltage.

6.3 Selective-Interruption (Discrimination)

Details selective interruption combinations for main and branch breakers.

6.4 Cascade Back-up Protection

Presents MCCB combinations for cascade interruption and their capacity.

6.5 I²t let-Through and Current Limiting Characteristics

Shows graphs of I²t let-through and current limiting characteristics for MCCBs.

6.6 Protective Coordination with Wiring

Discusses coordination formulas and considerations for conductor protection.

6.7 Protective Coordination with Motor Starters

Covers coordination between MCCBs and motor starter components for protection.

6.7.6 Motor Starting Current

Discusses motor starting current effects like DC transient and residual voltage.

6.8 Coordination with High-Voltage Devices

7. SELECTION

7.1 Motor Branch Circuit Selection

7.3 Main Circuit and Welding Circuit Selection

7.6 MCCBs for Capacitor (PF Correction) Circuits

7.7 MCCBs for Thyristor Circuits

7.8 Selection of MCCBs in inverter circuit

9. SHORT-CIRCUIT CURRENT CALCULATIONS

9.3 Impedances and Equivalent Circuits

Transformer, Wiring, and Bus-Duct Impedances

Total Impedances and Equivalent Circuits

9.5 Calculation Procedures