Tag: circuit breaker

DC Power(R)

Posted on by lechuck park

Data Center DC Power System Comprehensive Overview

This diagram illustrates the complete DC (Direct Current) power supply system for a data center infrastructure.

1. Core Components

① Power Source

  • 15.4 KV High Voltage AC Power
  • Received from utility grid
  • Efficient long-distance transmission (Efficient Delivery)
  • High voltage warning indicator (High Warning)

② Primary Transformer

  • Voltage conversion: 15.4 KV → 6.6 KV
  • Function: Steps down high voltage to medium voltage
  • Transformation method: Voltage Step-down
  • Adjusts voltage for internal data center distribution

③ Backup Power #1 – Generator System (Long-Time Backup)

  • Configuration: Diesel generator + Fuel tank
  • Characteristic: Long-duration backup capability
  • Purpose: Continuous power supply during main power outage
  • Advantage: Unlimited operation as long as fuel is supplied

④ Secondary Transformer

  • Voltage conversion: 6.6 KV → 380 V
  • Function: Steps down medium voltage to low voltage
  • Transformation method: Voltage Step-down
  • Provides appropriate voltage for UPS and final loads

⑤ Backup Power #2 – UPS System (Short-Time Backup)

  • Configuration: UPS + Battery
  • Characteristic: Short-duration instantaneous backup
  • Purpose: Ensures uninterrupted power during main-to-generator transition
  • Role: Supplies power during generator startup time (10-30 seconds)

⑥ Final Load (Power Use)

  • Output voltage: 220 V AC or 48 V DC
  • Target: Servers, network equipment, storage systems
  • Feature: Stable IT infrastructure operation with DC power

2. Voltage Conversion Flow

15.4 KV (AC)  →  6.6 KV (AC)  →  380 V (AC)  →  48 V (DC) / 220 V
  [Reception]   [Primary TX]   [Secondary TX]   [Final Conversion]

3. Redundant Backup Architecture

Two-Tier Backup System

Main Power (15.4 KV) ─────┐
                          ├──→ Transform ──→ Load
Generator (Long-term) ────┘
         ↓
    UPS/Battery (Short-term) ──→ Instantaneous uninterrupted guarantee

Backup Strategy:

  • Generator: Hours to days operation (fuel-dependent)
  • UPS: Minutes to tens of minutes operation (battery capacity-dependent)
  • Combined effect: UPS covers generator startup gap to achieve complete uninterrupted power

4. Operating Scenarios

Scenario 1: Normal Operation

Utility power (15.4KV) → Primary transform (6.6KV) → Secondary transform (380V) → UPS → DC load (48V)

Scenario 2: Momentary Power Outage

  1. Main power interruption detected (< 4ms)
  2. UPS battery immediately engaged
  3. Continuous power supply to load with zero interruption

Scenario 3: Extended Power Outage

  1. Main power interruption detected
  2. UPS battery immediately engaged (maintains uninterrupted power)
  3. Generator automatically starts (10-30 seconds required)
  4. Generator reaches rated capacity and replaces main power
  5. Generator power charges UPS + supplies load
  6. Long-term operation with continuous fuel supply

Scenario 4: Generator Failure

  • Limited-time operation within UPS battery capacity
  • Priority operation for critical systems or graceful shutdown

5. Additional Protection and Control Devices

Supplementary devices for system stability and safety:

Circuit Breaker Hierarchy

  • GCB (Generator Circuit Breaker): Primary protection at reception point
  • VCB (Vacuum Circuit Breaker): Vacuum interruption, medium voltage protection
  • ACB (Air Circuit Breaker): Low voltage distribution panel protection
  • MCCB (Molded Case Circuit Breaker): Individual load protection
  • Role: Circuit interruption during overload or short circuit to protect equipment and personnel

Switching Devices

  • STS (Static Transfer Switch): High-speed transfer between main power ↔ generator
  • ATS (Automatic Transfer Switch): Automatic transfer between power sources ( UPS level)
  • ALTS (Automatic Load Transfer Switch): Automatic load transfer ( for 22.9kV class)
  • CCTS: Circuit breaker control and transfer system
  • Role: Automatic/immediate transfer to backup power during power failure

Switching Points (Red circle indicators)

  • Reception point, before/after transformers, backup power injection points
  • Critical points for power path changes and redundancy implementation

6. Key System Features

✅ Uninterruptible Power Supply: Three-stage protection with main power → generator → UPS
✅ Multi-stage Voltage Conversion: Ensures both transmission efficiency and usage safety
✅ Automated Backup Transfer: Automatic switching without human intervention
✅ Hierarchical Protection: Stage-by-stage circuit breakers prevent cascading failures
✅ Scalable Architecture: Modular configuration enables easy capacity expansion

Summary

This DC power system architecture ensures continuous, uninterrupted operation of mission-critical data center infrastructure through a sophisticated combination of redundant power sources, automated failover mechanisms, and multi-layered protection systems. The integration of long-term generator backup and short-term UPS battery systems creates a seamless power continuity solution that can handle any grid interruption scenario. The multi-stage voltage transformation (15.4KV → 6.6KV → 380V → 48V DC) optimizes both transmission efficiency and end-user safety while providing flexibility for diverse IT equipment requirements.

#DataCenter #DCPower #PowerSystems #CriticalInfrastructure #UPS #BackupPower #DataCenterDesign #ElectricalEngineering #PowerDistribution #MissionCritical #DataCenterInfrastructure #FacilityManagement #PowerReliability #UninterruptiblePowerSupply #DataCenterOperations

With Claude