Strategic decisions in DC back-up design

Strategic decisions in DC back-up design

Battery & Charger Basics Factors that will influence their selection 02/29/20 When a battery is not just a battery And a charger is more than just a source of DC Prepared by Yves A. Lavoie 1 What are we talking about? Loads: Meters Relays Lights Tripping coils Charging motors Lube pumps Inverter 02/29/20

Prepared by Yves A. Lavoie 2 Battery basics History 3rd Century AD: The BAGHDAD Battery 1.1Vdc 02/29/20 Prepared by Yves A. Lavoie 3 Battery basics History 1800: Alessandro Volta Zinc-Silver in salty mix 1.1Vdc Volta demonstrates his results to Napoleon 02/29/20

Prepared by Yves A. Lavoie 4 History 1859: Gaston Plant The Lead-Acid battery Two lead foils separated by a rubber sheet in sulphuric acid (H2SO4) 02/29/20 Prepared by Yves A. Lavoie 5 Battery chemistry Basic Lead Acid secondary cell (rechargeable) Porous separator Electrolyte: Sulphuric acid, H2SO4 25%- Water H2O 75%

- Negative Plate Pb 02/29/20 + - + - Positive Plate PbO2 Prepared by Yves A. Lavoie 6 Battery chemistry Voltage Open Circuit Voltage is in direct relationship with the

concentration of sulphuric acid present in the cell Specific Gravity + 0.845 = Open circuit voltage Capacity Capacity is in direct relationship with the cells quantity of lead and the quantity of available sulphuric acid available to react with it. 1.24 S.Gr.+0.845=2.085 Vdc/Cell X 60 Cells= 125.1Vdc 02/29/20 Prepared by Yves A. Lavoie 7 Battery chemistry For the same quantity of lead Higher specific gravity

More Capacity Shorter life Smaller footprint for the same Ah rating Better adapted to Higher & Shorter discharge rates Less adaptable to Floating operation 02/29/20 Lower specific gravity Less capacity Longer life Larger footprint for the same Ah rating Better adapted to Longer & Lower discharge rates More adaptable to float operation Prepared by Yves A. Lavoie

8 02/29/20 Prepared by Yves A. Lavoie 9 Lead Acid Battery construction Flat Plate Low cost Excellent energy density Good mechanical strength Limited Life Limited cycling capability Tubular Plate Good energy density Superior cycling capability Longer life Lower high-rate performance Not the best suited for vibration Inability to see the positive

plate edges 02/29/20 Prepared by Yves A. Lavoie 10 Lead Acid Battery construction 2-Alloys Lead Calcium Excellent stability of the float characteristics Requires minimal watering Poor cycling (capacity likely to exhibit a marked reduction in less than 50 cycles) Positive grid growth Positive post seal problems Loss of active material

Subject to Passivation (Sudden Death). Requires regular testing Lead Selenium (Low Antimony 1.6 % or less) Major reduction of the Antimonial poisoning Good float charge characteristics over the life of the Battery Good cycling (800 to 1000 cycles typical) Requires slightly more watering than Lead calcium batteries 02/29/20 Prepared by Yves A. Lavoie 11 Vented Lead Acid Battery construction 1. 2. 3. 4. 5. 6.

7. 8. 9. 10. 11. 12. 13. 14. 15. 02/29/20 Prepared by Yves A. Lavoie Micro porous separators Positive plates Glass Mat Retainer Positive Plate support Positive & Negative Bus Bars Jar Cover Seal Electrolyte Sampling Tube Cover

Vent & filling tunnel Post Seal Negative Plate Jar Element support Electrolyte level lines Plate edge to wall Clearance 12 GEL Lead Acid Battery construction 02/29/20 Prepared by Yves A. Lavoie 13 GEL Lead Acid Battery construction 02/29/20 Prepared by Yves A. Lavoie

14 AGM or Absorbed Electrolyte Lead Acid Battery construction Plate group 02/29/20 Soldered plate group (Element) Prepared by Yves A. Lavoie 15 AGM or Absorbed Electrolyte Lead Acid Battery construction Elements Container 02/29/20 Prepared by Yves A. Lavoie

16 AGM or Absorbed Electrolyte Lead Acid Battery construction Cell connection Inserting Cover 02/29/20 Prepared by Yves A. Lavoie 17 Lead Acid Battery construction Absorbed Electrolyte (AGM) Available in 5, 10 or 20 years warranty Flat plate only In a Substation application you can expect 20 % to 50% of service life. In a UPS you can expect 10% to 40% of service life Advantages:

No water additions High energy density (Small footprint) Excellent High rate performance (Good for short time backup) Good cold weather performance (Because of high S.gr.) Excellent availability Low initial cost 02/29/20 Prepared by Yves A. Lavoie 18 Lead Acid Battery construction Absorbed Electrolyte 02/29/20 Disadvantages Extremely sensitive to AC ripple (causes micro-cycling)

All inside cell connections exposed to Oxygen (Negative bus corrosion) Open Cell failure more frequent than with any other Lead-Acid Mostly made with recycled Non 100% pure lead. Subject to Negative plate Self Discharge (Requires the use of Catalyst) Very sensitive to heat and dry out due to limited quantity or electrolyte. Having plates under mechanical pressure to insure perfect alignment and contact with the absorbed glass material increases inside stress. Subject to thermal run away Unpredictable due to Passivation (Sudden death) Very sensitive to deep discharge Longer charging times preferable

No Tubular plates Flat plates only Prepared by Yves A. Lavoie 19 Lead Acid Battery construction Absorbed Electrolyte Gelled Electrolyte Available in 12, 15 and 18 years design life Calcium alloy Flat plate Tubular plate In substation application you can expect 25 % to 100% of design life In a UPS application you can expect 15% to 70% 02/29/20 Negative plate corrosion. Unpredictable due to Passivation (Sudden death) Longer charging times required

Temperature compensation required Sensitive to AC ripple Higher initial cost Prepared by Yves A. Lavoie 20 Gelled Electrolyte Advantages No water additions All inside cell connections are immersed in Electrolyte Mostly made with new lead (Greatly reduces the risk of negative plate self discharge and the need for catalysts)

Good energy density Superior resilience to deep discharge Good cold weather performance Superior heat dissipation Less sensitive to heat and dry out Less subject to thermal runaway Less sensitive to deep discharges Excellent for solar application. After more than 18 months on float, production AGM cells continued to emit gas (ie: lose water) at rates too high to permit a 20 year life. The rates did not appear to be declining with time. Gel cells on the same test, but at a lower float voltage, had lower gas emission rates. INTELEC 1996 W.E.M. Jones, D.O. Feder: Behavior of VRLA Cells on long term float: Part 2 02/29/20 Prepared by Yves A. Lavoie 21 Vented vs. VRLA vs. Plate vs. Alloy What the market has to offer: Plate composition

Pure Lead Lead Calcium Lead Selenium Flat Plate (Grid plate) X X Tubular Plate X X Type of Battery Vented Lead Acid Plante X

Valve regulated Lead Acid (VRLA) Absorbed Electrolyte Cell (AGM) Flat Plate X X X Tubular plate Gelled Electrolyte Cell X Flat Plate X Tubular plate X 02/29/20 Prepared by Yves A. Lavoie

22 Battery Sizing Sizing and selection of lead-acid batteries should be performed according to ANSI/IEEE Std 485, IEEE Recommended Practice for Sizing Large Lead Storage Batteries for Generating Stations and Substations. A M P E R E S 320 300 280 260 240 220 200 180

160 140 120 100 80 60 40 20 L5 Random Load L2 0 L7 L4 L6 L3 Random Load

L7 L1 1 30 60 90 120 150 180 240 300 360 420 479

480 1 Min. MINUTES 02/29/20 Prepared by Yves A. Lavoie 23 Battery Sizing A M P E R E S 320

300 280 260 240 220 200 180 160 140 120 100 80 60 40 20 Random Load L1 0 L7

L6 L3 L4 Random L2 Load L7 L5 1 30 60 90 120 150 180

240 300 360 420 479 480 1 Min. MINUTES 02/29/20 Prepared by Yves A. Lavoie 24 Battery Sizing

Other selection factors recommended by ANSI/IEEE Std 485 are the following: 1. Physical characteristics, such as size and weight of the cells, container material, vent caps, intercell connectors, and terminals. 2. Planned life of the installation and expected life of the cell design. 3. Frequency and depth of discharge 4. Ambient Temperature. 5. Maintenance requirements for the various cell designs 6. Seismic characteristics of the cell design. 02/29/20 Prepared by Yves A. Lavoie 25 Parameter # 1 Environment, 4 Factors: A. Temperature B. Layout C. Ventilation D. Regulatory A. B.

02/29/20 Seismic Fire Protection Prepared by Yves A. Lavoie 26 Temperature The ambient temperature that your batteries will be exposed to will affect their performance, longevity and reliability In North America the reference temperature is 25 C (77 F), Batteries built according to IEC Standards are rated at 20 C (68 F), If the operating temperatures in your battery room vary from the norm by +/- 3 C you should add temperature compensation to your charger Batteries exposed to lower temperature will have lower performance and their sizing needs to be compensated Batteries exposed to higher temperatures will have a higher performance but a shorter life due to accelerated corrosion. The rule of thumb for decrease in life at higher temperatures is: Lead-Acid 50% of life removed for every 10 C Nickel-Cadmium 20% of life removed for every 10 C

02/29/20 Prepared by Yves A. Lavoie 27 Questions Temperature Will the battery room be climate controlled? Should we climate control the room? Do we need to add temperature compensation to our charger? Should we examine other battery technologies. 02/29/20 Prepared by Yves A. Lavoie 28 Layout 2 Factors will influence your battery layout Battery Blocks or individual cells

Blocks have a smaller footprint but due to a smaller ratio of electrolyte to lead surface their life is generally 10 to 20% shorter with vented batteries, 20 to 30% with gel and around 50% for AGM Individual cell monitoring may not always be possible If a cell is defective you have to replace the whole block Number of tiers and steps in your battery rack Racks that are narrow and high will expose batteries to temperature variations. These variation will cause some batteries to be undercharged wile others will be overcharged. Over time the imbalance is going to worsen and your systems reliability and battery life will be jeopardized. If you have no choice, install a fan above the batteries. 02/29/20 Prepared by Yves A. Lavoie 29 Questions Layout Are we going to use single cells or blocks? Will we sacrifice battery reliability and life to footprint ?

02/29/20 Prepared by Yves A. Lavoie 30 Ventilation Do I need to ventilate or not? The Battery Technology If we use vented batteries we will need to determine the quantity of hydrogen generated by the battery versus the number of air changes in the battery room It is generally accepted knowledge that VRLA batteries, under normal circumstances do not require ventilation when installed in a regular room... High volt shutdown If your charger was not specified with a Hi-Volt Shutdown we recommend that the rooms air changes be verified against the possible Hydrogen and Oxygen generation of the battery if it is exposed to the voltage of a charger that would have lost regulation... +/- 162 Vdc

02/29/20 Prepared by Yves A. Lavoie 31 Questions Ventilation Are we going to ventilate? How much hydrogen will my battery generate under the worst case scenario? Does the battery room have enough air changes to compensate How do I ventilate All the time When the batter reaches a certain voltage (Charger activated) Do I install a hydrogen detection device with a contactor to activate the fan I am installing VRLAs do I need to ventilate? Worst case scenario... Does my charger spec call for a charger equipped with high volt shutdown? 02/29/20

Prepared by Yves A. Lavoie 32 Parameter # 2 Load profile, 3 factors: A. Loads B. Backup time C. Voltage window 02/29/20 Prepared by Yves A. Lavoie 33 Loads There are different loads to be carried by the battery during a loss of AC.

Trip & Close solenoids + Spring charging motors Meters + Protection relays + Lights DCS / SCADA systems + telecom Lube Pump Inverter for AC loads Others? Loads have to be structured in a coherent manner so that the battery can be sized 02/29/20 Prepared by Yves A. Lavoie 34 What is the structure of my load profile? Amperes Amperes Time Time

Amperes Amperes Time Amperes Time Amperes Time 02/29/20 Prepared by Yves A. Lavoie Time 35 Questions Loads

What are my loads? What will be the structure of my load profile How often will the batteries be cycled 02/29/20 Prepared by Yves A. Lavoie 36 Backup time 5 factors will influence the required length of your backup time: The time required to stop a $$$ uninterruptable process Aluminum smelter... Mine... Any high revenue generating process The time to repair a failed charger (Could lead to redundancy) If spare chargers or spare parts are not available, your protection will last as long as your batteries.

AC fail duration worst case scenario vs. alternate scenario Historical data maybe useful... Availability of alternate AC sources If you have a generator on site... Twin feeds from alternate sources... Legislation 02/29/20 In some regions 24 hours! For some applications the NRC is contemplating up to72 hours Prepared by Yves A. Lavoie 37 Questions Backup time Do I have an application related minimum? What is the worst case scenario for a charger repair? Is the cost of a battery with a longer backup time to high

in comparison to redundant chargers? What is the longest blackout that I need to plan for? Do I have or want an alternate AC source (Standby generator or a second utility feed)? Are there regulatory parameters that I need to consider? 02/29/20 Prepared by Yves A. Lavoie 38 Voltage window The voltage window of each equipment will determine the highest voltage that my can be charged at: V(max) (130 Vdc) / Equalize voltage per cell (1.47 Vdc) = maximum number of cells (88 Cells) V(max) (140 Vdc) / Equalize voltage per cell (2.40 Vdc) = maximum number of cells (58 Cells) V(max) (140 Vdc) / Equalize voltage per cell (2.33 Vdc) = maximum number of cells (60 Cells) Question What is the operating voltage window of each

equipment? 02/29/20 Prepared by Yves A. Lavoie 39 Parameter #3 Monitoring & Maintenance To monitor and maintain or not... 02/29/20 Prepared by Yves A. Lavoie 40 To maintain or not? If you decide to monitor & maintain Different batteries have different monitoring & maintenance needs If qualified personnel is difficult to hire, think about training your current personnel . If hiring or training is not feasible, what about automation or even partial automation coupled with farming out the balance of the tasks.

If you decide not to maintain you will still need to monitor Over 100 years of experience has shown that BATTERIES CAN AND WILL FAIL sometimes less than 3 months after installation. If a battery monitoring system is chosen who will analyse the data, who will respond to the alarms? If you do not want to maintain or buy a monitoring system ensure that you specify a charger with the proper test and alarm features. Your choice of battery technology should be influenced by the decision you just took above 02/29/20 Prepared by Yves A. Lavoie 41 To maintain or not? Vented Visual Inspection

VRLA Signs of corrosion or sulphation Post growth or seal leaks Cracked covers or jars Water replenishment Specific gravity readings Cell or block Voltage readings

Cell or block Ohmic measurement Battery continuity test Verify torque measurements Connector & Post resistance Temperature measurement (Battery or Ambient) Battery capacity / Service test 02/29/20 Visual Inspection Post growth or seal leaks Cracked covers or jars Bloated covers or jars Cell or block Voltage readings Cell or block Ohmic measurement Battery continuity test Verify torque measurements

Connector & Post resistance Temperature measurement (Battery or Ambient) Battery capacity / Service test Prepared by Yves A. Lavoie 42 QUESTION To maintain or not? How will I take care of my batteries 02/29/20 Prepared by Yves A. Lavoie 43 Parameter # 4 Battery technology Choosing the right battery for my application 02/29/20

Prepared by Yves A. Lavoie 44 Choosing the right battery for my application Criticality of the application The environment my batteries will be in Load profile Maintenance environment Initial budget versus life-cycle cost 02/29/20 Prepared by Yves A. Lavoie 45

Choosing the right battery for my application Initial budget vs. Lifecycle cost 1. $Automotive, Marine deep cycle. (Emergency patch for a week or two) 2. $$$ 5 year design life AGM (1.5 to 2.5) 3. $$$$ 10 year design life AGM (2 to 5) 4. $$$$$ 20 year design life AGM (6 to 10) 5. $$$$$ Flat plate Gel OGiV (Thin Plate) (10 to13) 6. $$$$$ Tubular plate Gel OPzV (15 to 20) 7. $$$$$$ Vented Flat plate Calcium (Thick plate) ( 12 to 20) 8. $$$$$$ Vented Tubular plate Calcium (15 to 20) 9. $$$$$$ Vented Flat plate Selenium Ogi (Thin plate) 15 to 20 10. $$$$$$ Vented Tubular plate Selenium OPzS (15 to 25) 11. $$$$$$$$$$$ Vented Plant ( 25+) 12. $$$$$$$$$$$ Low maintenance Nickel cadmium (20+) 13. $$$$$$$$$$ Vented Nickel cadmium (20+) 14. $$$$$$$$$$$$$ Lithium Ion (20+) 02/29/20 Prepared by Yves A. Lavoie 46

QUESTIONs Choosing the right battery for my application What is the right battery technology for my application 02/29/20 Prepared by Yves A. Lavoie 47 Parameter # 5 The dc power required by the application and the battery Basic alarms & functions & characteristics AC Fail Rectifier fail Combination of Low Volt & Low current High Volt dc High Volt shutdown

To protect your investment Low Volt dc Your battery is discharging Your battery has finished discharging Low current dc Your dc system is no longer feeding one of your circuits Ground fault Temperature compensation &High & Low Battery temperature alarm &Delta temperature alarm So that your battery always receives the optimal float voltage High ripple alarm

02/29/20 To know when it is time to replace the chargers filtering output capacitors To insure that your batteries do not get micro-cycled Prepared by Yves A. Lavoie 48 The dc power required by the application and the battery Other needs! Event log with date & time stamp Know everything that has occurred to your system Better diagnostics Protection for your battery warranty Float current monitor

Float current increases as battery ages. Premature rise in current coupled to a rise in temperature is an early warning of thermal run away Digital Ampere/hour meter Positive and negative current monitoring Real time knowledge of battery state of charge Battery continuity test Can your battery deliver the high current needed to trip the breakers? Battery Service test 02/29/20 Can your battery keep your loads operational as long as intended? Prepared by Yves A. Lavoie

49 QUESTIONs Charging needs of my battery & application Is a plain charger what I really need? How can I secure a safer system whithout breaking the bank? 02/29/20 Prepared by Yves A. Lavoie 50 CONCLUSIONS ASK THE RIGHT QUESTIONS = GET THE RIGHT ANSWERS = MAKING THE RIGHT CHOICE A CAREFULLY WRITTEN SPECIFICATION IS YOUR BEST PROTECTION AGAINST GREED 02/29/20 Prepared by Yves A. Lavoie

51 What are the costs associated to system failure? 1. Are lives at stake? 2. Are non interruptible processes involved? 3. Are major financial losses a possibility? 4. What risk level is acceptable? 5. What is the available budget and Is it in line with the risk level? 02/29/20 Prepared by Yves A. Lavoie

52 For more information IEEE standards, recommended practices and guides. Attend as many stationary battery events as possible: Infobatt, Battcon, Intelec. More than 15 years of papers archived on the Battcon website Become a member of the IEEE stationary battery committee: http://www.ewh.ieee.org/cmte/PES-SBC 02/29/20 Prepared by Yves A. Lavoie 53 Thank you! Yves Lavoie Primax Technologies Inc. 65 Hymus Boul. Pointe-Claire, QC H9R 1E2 514-459-9990 # 2004 [email protected]

02/29/20 Prepared by Yves A. Lavoie 54

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