IEEE PES SBC Winter Meeting. January 11 – 15, 2014. New Orleans, LA Technical Panel Session. Sunday January 11, 2015. DC System Failure Modes Part 2 IEEE PES SBC Winter Meeting. January 11 – 15, 2014. New Orleans, LA

Typical DC Power System Batteries Discussion: Types of Battery Battery Disconnects Low Voltage Disconnects Battery Disconnect Batteries Low Volts Disconnect IEEE PES SBC Winter Meeting. January 11 - 15, 2014. New Orleans LA

Typical DC Power System Battery Disconnect. A provision for disconnecting an entire battery plant and/or Individual battery strings from the system for: Maintenance Over current protection. Battery Cell Replacement. Two basic types of battery protection. Not to be confused with a battery low-voltage disconnect. Can be stand alone or integrated. Can be a switch with a fuse in-line or a circuit breaker IEEE PES SBC Winter Meeting. January 11 - 15, 2014. New Orleans LA

Typical DC Power System Low-Voltage Disconnect Provides a means to disconnect the battery from the load to prevent over discharge. Either the load or the batteries can be disconnected. Multiple LVD’s in the load line allow sequenced load shedding – keep revenue earning loads powered longer. Non-essential load Essential load LVD in battery line LVD’s in load lines IEEE PES SBC Winter Meeting. January 11 - 15, 2014. New Orleans LA

DC System Failure Modes Somewhat Unique to Telecom? Curtis Ashton IEEE PES StaBatt Winter 2015 (Jan 11) mtg Sunday Technical Panel Sessions IEEE PES SBC Winter Meeting. January 11 - 15, 2014. New Orleans LA

IEEE PES SBC Winter Meeting. January 11 - 15, 2014. New Orleans LA Overview Things the Telecom Industry Does Differently Thanks to the FCC FCC Best Practices No Battery Disconnects in COs What this means for Grounding Cable Sizing No LVDs in COs What This Does to Batteries on OverDischarge IEEE PES SBC Winter Meeting. January 11 - 15, 2014. New Orleans LA

A Couple of Relevant FCC Best Practices 8-7-0676 Network Operators Should Not Use Battery Disconnects at CO Battery Plants Network Operators Should Not Use LVDs at CO Battery Plants IEEE PES SBC Winter Meeting. January 11 - 15, 2014. New Orleans LA

Battery Disconnects Required by NEC Outside COs Commonly Used Where NEC “Not Covered” Exemptions for Telecom/Utility Don’t Apply e.g. Business Customer Premises, or Collocation Hotels IEEE PES SBC Winter Meeting. January 11 - 15, 2014. New Orleans LA

Frame Grounding of Trays/ Racks/Stands w/Brkr Disconnect Per NEC 250.122 Max Ampacities Per 310.15B17 (Single Conductor) or 610.14A (30-min Multi-Wire) Typical Disconnect Brkr Size Typical Ah Typical Short Ckt Amps Ground AWG Typical Ampacity 40 100 4,000 10 30 300 12,000 8 70 400 1200 18,000 2 173 600 1680 24,000 1/0 259 1000 3000 30,000 2/0 294 4000 40,000 4/0 399 IEEE PES SBC Winter Meeting. January 11 - 15, 2014. New Orleans LA

Typical Breaker I-t Curve IEEE PES SBC Winter Meeting. January 11 - 15, 2014. New Orleans LA

CO #6 AWG Rack Ground Wire IEEE PES SBC Winter Meeting. January 11 - 15, 2014. New Orleans LA

Burnt Up on Short Circuit IEEE PES SBC Winter Meeting. January 11 - 15, 2014. New Orleans LA

IEEE PES SBC Winter Meeting. January 11 - 15, 2014. New Orleans LA LVDs LVD Contactors Keep Batteries from Damage Due to OverDischarge Typically Keep Telecom Batteries Above 1.75 V/cell At Least One Battery Manufacturer Has LVDs as a Requirement for Honoring Standard Warranty LVLDs vs LVBDs False Operations In Telecom Led to More Adoption of LVBDs After Electronics Changed to Prevent Burnup More False Operations (even of LVBDs) Led to FCC Best Practice for COs We’d Rather Sacrifice the Batteries, But Keep Loads Working LVBDs Still Sometimes Used Outside the CO Depending on Company Practice and Priorities IEEE PES SBC Winter Meeting. January 11 - 15, 2014. New Orleans LA

IEEE PES SBC Winter Meeting. January 11 - 15, 2014. New Orleans LA Damage w/o LVDs While Most Telecom Equipment Shuts Itself Off Before Battery Max Discharge Avg of 1.67 V/Cell, Some will allow Draining Batteries Below 1.0 V/Cell IEEE PES SBC Winter Meeting. January 11 - 15, 2014. New Orleans LA

Typical DC Power System Batteries Two Main Chemistries: Lead-Acid Nickel - Cadmium IEEE PES SBC Winter Meeting. January 11 - 15, 2014. New Orleans LA

Typical DC Power System Batteries Two Main Types: Valve-regulated. (Out gassing is limited by a pressure relief valve). Vented. The gasses are allowed to vent from the battery. They are available in both lead-acid and nickel cadmium IEEE PES SBC Winter Meeting. January 11 - 15, 2014. New Orleans LA

Typical DC Power System Batteries Three main types of Vented Lead-Acid Batteries: Vented Planté (Pure Lead) Plate Vented Flat (Pasted) Plate Calcium, Selenium, and Antimony Tubular Plate IEEE PES SBC Winter Meeting. January 11 - 15, 2014. New Orleans LA

Typical DC Power System Typical VLA (Flooded) Battery Systems Note Spill Containment IEEE PES SBC Winter Meeting. January 11 - 15, 2014. New Orleans LA

Typical DC Power System Batteries Two Main Types of Valve-Regulated Lead-Acid (VRLA) Batteries: Absorbed (starved) Electrolyte Gelled Electrolyte These are mostly Lead-Calcium but some contain other alloys. IEEE PES SBC Winter Meeting. January 11 - 15, 2014. New Orleans LA

Typical DC Power System Typical VRLA 20 Year Batteries. Large 48 Volt Plant Small 24 Volt Plant IEEE PES SBC Winter Meeting. January 11 - 15, 2014. New Orleans LA

Typical DC Power System Typical 10 Year Front Terminal Batteries IEEE PES SBC Winter Meeting. January 11 - 15, 2014. New Orleans LA