RELIABILITY Power Systems Ni-Cd Batteries Div. DS Ver.3.11/ Jan 2011 Page 1/20

Transcription

1 RELIABILITY Power Systems Ni-Cd Batteries Div. DS Ver.3.11/ Jan 2011 Page 1/20

2 RELIABILITY NICKEL CADMIUM BATTERIES Owing to the structural materials they use, RELIABILITY Nickel Cadmium (Ni-Cd) Batteries are exceptionally robust and free from risk of sudden failure. The higher power application Ni-Cd Batteries electrodes are made of high yield plates thereby increasing cell efficiency. The Ni-Cd Batteries are rechargeable and can delivering high power during discharge cycle. With capacities ranging from 0.1AH to 2500AH RELIABILITY manufactured Nickel-Cadmium Batteries are widely used for Commercial, Military and Industrial application for decades. RELIABILITY Power Systems is an active green-energy partner and contributes to environmental protection by utilizing increasing proportion of Cadmium from Recycled Batteries. Nickel-Cadmium Batteries have a legendary reputation for robustness, reliability and service life. This is the benchmark technology for difficult and demanding applications: operating temperatures from 40 C to +60 C (because the electrolyte has a very low freezing point), excellent cycling capability (up to 5,000 cycles), long storage life, and low maintenance.. CONSTRUCTION: The positive Terminal (Anode) of RELIABILITY Nickel-cadmium Batteries are made of Cadmium Hydroxide and Negative Terminal (Cathode) with Nickel Hydroxide. These electrodes/plates are immersed in an Alkaline Solution (Electrolyte) which consists of Lithium, Potassium and Sodium Hydroxides. Depending on application, Ni-Cd batteries are manufactured with various electrode technologies such as Pocket-Type and Sintered Plate or PBE (Plastic Bonded Electrodes) Anodes and cathodes. Low-Maintenance Sealed and Vented both types Nickel-Cadmium cells are available. Cylindrical Nickel-Steel Cans are used for sealed cells whereas Prismatic flame retardant Plastic Casing is used for Vented Cells. RELIABILITY Power Systems Ni-Cd Batteries Div. DS Ver.3.11/ Jan 2011 Page 2/20

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4 K SERIES NICKEL-CADMIUM BATTERIES TYPES: RELIABILITY K Series Nickel-Cadmium Batteries are available in four different types which can be selected according to application and Autonomy Time requirements. Following is a brief summary of all four types: 1. REL-KPX (Ultra High Discharge Rate Cells) 2. REL-KPH (High Discharge Rate Cells) 3. REL-KPM (Medium Discharge Rate Cells) 4. REL-KPL (Low Discharge Rate Cells) REL-KPX TYPE (Ultra High Discharge Rate Cells): KPX Series ultra high rate nickel cadmium battery, which is made of sintered plates, is characterized as having compact construction, low internal resistance, high reliability, high capacity, long service life, and excellent low temperature performance. The battery is suitable for ultra high discharge rate applications such as AGV, engine starting, switch tripping and closing, etc. REL-KPH TYPE (High Discharge Rate Cells): KPH Series high rate nickel cadmium battery is made of pocket plates. It has the characteristics of thin plates, high porosity, and low internal resistance. The battery is particularly suitable for high discharge rate applications such as UPS, switchgear tripping and closing, etc. REL-KPM TYPE (Medium Discharge Rate Cells): KPM Series medium rate nickel cadmium battery is made of pocket plates. The battery is suitable for medium discharge rate applications (between 30 minutes to 5 hours) such as railroad DC power sources, UPS, gas turbine control, etc. REL-KPL TYPE (Low Discharge Rate Cells): KPL Series low rate nickel cadmium battery is made of pocket plates. The battery is designed for general purpose and standby applications such as lighting on trains, operation of circuit breaker, UPS Systems, Telecom Systems etc. RELIABILITY Power Systems Ni-Cd Batteries Div. DS Ver.3.11/ Jan 2011 Page 4/20

5 RELIABILITY K-Series Ni-Cd Batteries Recommended Selection of Type based on Autonomy Time Requirements: RELIABILITY Ni-Cd Batteries Charging The most common type of charging for stationary batteries is modified constant voltage, usually with current limitation of 0.2I A or 0.1I A (C/5 or C/10). The battery is connected to the charger directly which applies a constant voltage across the Battery Terminals. RELIABILITY Power Systems Ni-Cd Batteries Div. DS Ver.3.11/ Jan 2011 Page 5/20

6 Recommended Charging Voltage: The RELIABILITY Ni-Cd Cells are recommended to be charged according to following table: K-SERIES Ni-Cd BATTERIES COMMISSIONING/ INITIAL CHARGING: The initial charging during commissioning of Nickel-Cadmium Batteries is based on constant current method. The K-Series Nickel-Cadmium Batteries are recommended to be initially charged with following parameters: o.2i, for 10 hours rate 0.1,A for 20 hours rate As with other Nickel-Cadmium batteries, the RELIABILITY K-Series Ni-Cd Batteries Charging Time is Inversly proportional to the Charging Current which is set by the current limit of Charging apparatus. RELIABILITY Power Systems Ni-Cd Batteries Div. DS Ver.3.11/ Jan 2011 Page 6/20

7 COMPUTATION METHOD FOR SELECTING A Ni-Cd BATTERY: Data Required for Battery Capacity Calculation: For a precise Battery Calculation, the following information is required: System Nominal Voltage Load Current Autonomy Time/ Standby Period Minimum Voltage (EOD) Maximum Voltage Temperature Range Installation Layout Float Voltage Operation: Ni-Cd Battery Float Voltage is selected based on the type of Battery required: No. of Cells required= System Voltage/Cell Float Voltage Minimum Cell Voltage= System Minimum DC Voltage/No. of Cells The most commonly used Cell Voltages are 1.40 to 1.48 Voltage per Cell (VPC), however the precise voltages are computed based on actual requirements. EXAMPLE A RELIABILITY Ni-Cd Battery is required to provide backup Power for a UPS Inverter with 20KVA load. The Load has a Leading Power Factor of 0.8 and UPS-Inverter has an Efficiency of The Inverter operates between 202V (the minimum Voltage) and 265V (the maximum voltage). The Autonomy Time required is 2-hrs at Normal Room Temperature. Battery required would be: Battery Power Required = Inverter KVA x Power Factor/ Inverter Efficiency Computing the data in above equation yields: Battery Power Required=17,170W (or 1.44VPC the No. of Cells Required would be= 265/1.44 = 184 Cells Minimum Cell Voltage = EOD Voltage / No. of Cells = 202/184 = 1.1 VPC Maximum Battery Current = Battery Power Required / Min. Cell Voltage x No. of Cells = 17170/1.10 x 184 = 85 Amperes The battery to be selected should have capacity equal or above the calculated value. Based on Autonomy Time (2-hrs), the Battery will be RELIABILITY KPL Type (see page-4). Based on Discharge Current the selected Battery is KPL250 (See KPL Batteries Data Sheet on Page-18). Determining No. of Battery Cells: The No. of Cells in a Battery Bank is determined by dividing the System Nominal Voltage with the Single Cell Voltage (1.2V): RELIABILITY Power Systems Ni-Cd Batteries Div. DS Ver.3.11/ Jan 2011 Page 7/20

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12 Discharge Current and Time of discharge when battery is fully RELIABILITY Power Systems Ni-Cd Batteries Div. DS Ver.3.11/ Jan 2011 Page 12/20

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