'critical power applications'

Powerstack batteries, typically used in UPS systems, inverters, and other energy storage applications, require proper testing and maintenance to ensure their efficiency, longevity, and reliability. If you need to perform battery testing on a Powerstack battery, here's a general guide for testing and monitoring its condition: Steps to Test Powerstack Batteries: 1. Visual Inspection Check for Physical Damage: Inspect the battery casing for any cracks, leaks, or bulges. Damaged batteries should be replaced. Clean the Terminals: Ensure the terminals are clean and free from corrosion. If there is any corrosion, clean the terminals with a mixture of baking soda and water. 2. Check Battery Voltage Measure the Open-Circuit Voltage (OCV): Use a digital voltmeter to measure the voltage across the battery terminals when it is not connected to any load. Compare the measured voltage to the battery’s rated voltage. A typical fully charged 12V lead-acid battery should read around 12.6 to 12.8 volts. For a 24V battery, you should see a voltage of around 25.2 to 26.0 volts. Undercharged Battery: If the voltage is significantly lower (e.g., 10.5V or less for a 12V battery), it may indicate that the battery is undercharged or faulty. 3. Load Testing Test under Load: Apply a load to the battery, simulating its normal working conditions. The load can be an inverter or UPS system that draws power from the battery. Monitor the voltage drop under load. The voltage should not drop drastically; otherwise, it may indicate that the battery is aging or weak. DC Discharge Test: If you have access to a battery analyzer or tester, you can perform a discharge test by applying a constant load and measuring the time it takes for the battery to reach a certain voltage cutoff. 4. Battery Charge Test Charge the Battery Fully: Use the manufacturer’s recommended charger to fully charge the battery. Most Powerstack systems will charge to full capacity in 6-12 hours, depending on the charger and battery size. Monitor Charging Parameters: If the battery doesn’t charge properly or takes longer than usual, it might indicate problems with the battery or the charger. End of Charge Voltage: For lead-acid batteries, the end-of-charge voltage should be around 14.4 to 15.0 volts for a 12V battery and 28.8 to 30.0 volts for a 24V battery. 5. Conduct a Specific Gravity Test (for Lead-Acid Batteries) Hydrometer Test: If your Powerstack battery is a lead-acid type, you can measure the specific gravity of the electrolyte inside the battery using a hydrometer. A fully charged battery will have a specific gravity of around 1.265 – 1.280. If the reading is low, it may indicate that one or more cells are faulty. 6. Perform a Battery Health Check (Advanced) Use a Battery Tester: There are advanced battery testers that can measure the internal resistance, capacity, and health of the battery. These testers usually simulate various load conditions and measure how well the battery performs. Internal Resistance: A higher internal resistance indicates aging and reduced capacity. A proper battery tester will show you this resistance reading, which helps in assessing the battery's remaining life. 7. Monitor for Temperature Batteries can heat up during charging and discharging. Check for unusual temperature rises that may indicate internal problems. Excessive heat can degrade battery life and may signal an issue with the battery or the charging system. Signs of a Failing Battery: Rapid Voltage Drop: If the voltage quickly drops under load, the battery is likely deteriorating. Short Runtime: If the battery runs out of charge much faster than expected, it could mean it's near the end of its life. Inconsistent Voltage Readings: Large fluctuations in voltage readings, especially when under load, can indicate a failing battery. Physical Damage: Swelling, leaks, or any visible damage to the battery indicates that it needs to be replaced. Battery Maintenance Tips: Regular Charging: Avoid deep discharges and always keep the battery charged. Environmental Conditions: Keep the battery in a cool, dry place to avoid overheating or damage due to extreme temperatures. Periodic Tests: Test the battery every 3-6 months to assess its health and ensure it’s functioning properly. Use the Right Charger: Always use the manufacturer's recommended charger to prevent overcharging or undercharging. Conclusion: Battery testing is critical for ensuring that your Powerstack battery continues to perform optimally. Regular testing helps in identifying potential problems early and maintaining the battery’s health. Always follow the manufacturer’s instructions and consult with a professional if you're unsure about the testing process.

The Vertiv Liebert Powerbank 600 is a modular and scalable uninterruptible power supply (UPS) solution designed for critical applications, particularly in data centers and telecommunications. It provides reliable power protection and is known for its flexibility and efficiency. Key Specifications Model: Liebert Powerbank 600 Capacity: 600 kVA Input Voltage: Typically supports 380/400/415 V three-phase systems Output Voltage: Configurable based on system requirements Form Factor: Modular design for easy scalability Efficiency: High efficiency, often exceeding 95% in double conversion mode Features Modular Design: Allows for easy expansion and maintenance, enabling users to add or replace modules as needed. High Availability: Designed for redundancy and reliability, ensuring continuous power supply to critical loads. Advanced Monitoring: Equipped with a user-friendly interface and remote monitoring capabilities for real-time performance tracking. Flexible Configuration: Supports various configurations to meet specific power requirements and environmental conditions. Battery Management: Intelligent battery management features to optimize battery life and performance. Scalability: Can be configured for parallel operation to increase capacity and redundancy. Compact Footprint: Designed to maximize power density in limited spaces, making it suitable for various installation environments. Applications Data Centers: Provides robust power protection for critical IT infrastructure. Telecommunications: Ensures uptime for communication systems. Industrial Applications: Safeguards sensitive equipment in manufacturing and processing environments. Performance Metrics Input Frequency: Typically supports 50/60 Hz Output Power Factor: Generally rated at 0.9, allowing for efficient power delivery. Operating Temperature: Designed to operate in a range of 0 to 40 degrees Celsius. Conclusion The Vertiv Liebert Powerbank 600 is a reliable and efficient UPS solution for businesses that require uninterrupted power supply for their critical applications. Its modular design, advanced features, and scalability make it suitable for a wide range of environments, ensuring that essential systems remain operational during power disturbances. For specific model details and configurations, it is advisable to consult the official Vertiv documentation or a local distributor.

The Vertiv 6kVA PowerBank UPS is typically part of Vertiv's On-Line or Line-Interactive power protection solutions that integrate battery backup systems designed to maintain a continuous supply of power in the event of an outage. These UPS systems are ideal for applications where consistent power quality and uptime are critical, such as for medium to large businesses, IT infrastructure, and high-demand environments like data centers. Although "PowerBank" is a brand name or marketing term used by Vertiv for specific models of UPS systems (often focused on extended battery runtimes or integrated external batteries), detailed product specifications and the exact model can vary. Below is a general overview of the Vertiv 6kVA PowerBank UPS based on the series features typically associated with Vertiv's offerings. Key Features and Specifications: 1. Topology: Double Conversion On-Line: Provides the highest level of protection by continuously filtering and conditioning the incoming utility power. It delivers pure sinewave output, making it suitable for sensitive equipment that requires high-quality power. The On-Line topology ensures zero transfer time in case of power failure because the UPS system is always supplying power from the inverter. 2. Power Rating: 6kVA / 6000VA (Provides backup for medium-sized systems or higher power applications like small-to-medium server rooms, network systems, and critical equipment). 3. Output Power: Output Power: 4.8 kW to 5.4 kW (depending on load and configuration) 4. Input and Output Specifications: Input Voltage: 110V - 300V, wide input range for handling fluctuations without switching to battery mode. Output Voltage: 230V ± 2% (standard in most countries) 5. Waveform Type: Pure Sinewave Output: Ensures that the connected equipment receives a smooth and continuous power supply without the distortions found in some lower-quality UPS systems. 6. Battery Configuration: Battery Type: Typically Sealed Lead-Acid (SLA) or Valve-Regulated Lead-Acid (VRLA) batteries. Battery Capacity: Typically, 12V batteries with 18Ah, 24Ah, or higher capacities. The system may include external battery modules (Battery Banks) for extended runtime, making it suitable for larger power demands and longer backup times. External Battery Packs: Some models support additional external battery cabinets, which allow the UPS to run longer during extended outages. This is especially important for environments where power failures may last for an extended period. 7. Charging Time: Typically, the system will fully recharge in around 4-6 hours, depending on battery size and environmental conditions. 8. Backup Time (Runtime): The backup time can range from 20 minutes to several hours, depending on the load. For example, a 50% load (about 3 kVA or 3000W) will generally offer a longer runtime. A full load of 6kVA will typically provide 10-15 minutes of backup time. If the UPS is configured with external battery packs, the runtime can be extended for much longer periods, making it ideal for critical systems that require extended protection during power outages. 9. Cooling System: The UPS is equipped with fan-assisted cooling to ensure efficient heat dissipation and prevent overheating during extended use. 10. Display and Monitoring: LCD Display: Displays real-time information about UPS status, battery health, load capacity, input/output voltages, battery runtime, and other important parameters. Audible Alarms: Alerts for conditions such as low battery, overload, power failure, and system faults. Smart Battery Management: Ensures optimal battery health and extends the lifespan of the UPS. 11. Connectivity and Interfaces: USB/Serial Ports: For communication with a connected computer or server for monitoring and management. SNMP Slots: Some models may offer SNMP (Simple Network Management Protocol) support for remote monitoring and management via networked devices. Dry Contact Interface: Allows integration with building management or alert systems. Optional Software: Available for automated shutdown in the event of prolonged power outages, and event logging. 12. Form Factor: Tower or Rackmount (depending on the specific model and user preferences). Some models are available in rackmount configurations for server rooms and data centers, while others are more suitable for a tower setup. 13. Additional Features: Overload Protection: Safeguards against exceeding the UPS's rated capacity. Short-Circuit Protection: Provides defense against electrical faults. Automatic Voltage Regulation (AVR): Ensures that the UPS compensates for voltage fluctuations (e.g., brownouts or overvoltages) without resorting to battery backup.

Vertiv PowerBank 600 kVA Online UPS The Vertiv PowerBank 600 kVA Online UPS is designed for critical power applications, particularly in data centers and industrial environments. Here’s a comprehensive overview of its specifications, features, benefits, and considerations: Overview The Vertiv PowerBank 600 kVA UPS provides robust, uninterrupted power supply with advanced features for high availability, power quality, and energy efficiency. Key Specifications Power Rating: 600 kVA Input Voltage: Typically 400/415V (three-phase) Output Voltage: 400/415V (three-phase) Frequency: 50/60 Hz (auto-sensing) Topology: Online double-conversion Efficiency: Up to 95% in normal operation and can reach 98% in eco mode Total Harmonic Distortion (THD): Typically <5% at full load Battery and Runtime Battery Type: Usually utilizes VRLA (Valve-Regulated Lead Acid) or Lithium-ion batteries Battery Configuration: Configurable based on requirements, with options for extended runtime Charging Time: Typically 4-8 hours for a full charge, depending on the battery type Runtime: Customizable based on load; options available for longer runtimes (requires additional battery packs) Features Advanced Monitoring: LCD display for real-time monitoring of status, input/output voltage, load percentage, battery status, and alarms. Redundancy: N+1 configuration for enhanced reliability and availability. Scalability: Capable of parallel operation with multiple units for increased capacity and redundancy. Smart Communication: SNMP, USB, and RS232 interfaces for remote management and monitoring. Bypass Switch: Manual bypass switch allows for maintenance without downtime. Hot-Swap Batteries: Some configurations allow for battery replacement without turning off the UPS. Physical Characteristics Dimensions: Varies by model; typically around 120-150 cm in width and depth. Weight: Approximately 600-800 kg, depending on the configuration and battery type. Cooling: Generally air-cooled; ensure proper ventilation in the installation area. Benefits Power Quality: Provides clean, stable, and regulated power to sensitive equipment. High Availability: Designed for critical loads requiring uninterrupted power supply. Energy Efficiency: High-efficiency modes help reduce operational costs. User-Friendly: Intuitive interface and comprehensive management software facilitate easy operation. Considerations Installation: Professional installation is recommended to optimize configuration and ensure compliance with electrical standards. Maintenance: Regular inspections and battery maintenance are crucial for ensuring reliability and longevity. Environmental Conditions: Requires proper ventilation and should be installed in a climate-controlled environment to avoid overheating. Cost: Initial investment can be substantial; consider the total cost of ownership, including maintenance and energy savings. Applications Data Centers Telecommunications Infrastructure Industrial Power Applications Medical Facilities Financial Institutions Conclusion The Vertiv PowerBank 600 kVA UPS is a powerful and reliable solution for ensuring continuous power supply and protecting critical infrastructure.

The Vertiv 5kVA UPS (Uninterruptible Power Supply) is designed to provide reliable backup power for critical equipment, protecting them from power outages, surges, and other electrical disturbances. Vertiv is known for providing high-quality power management solutions, and a 5kVA UPS typically serves small to medium-sized applications such as: Server rooms Small data centers Telecommunication equipment Networking devices Medical equipment Key Features of a Vertiv 5kVA UPS: Power Capacity: 5kVA (Kilovolt-Ampere) translates to 5000 Volt-Amperes. This is roughly equivalent to 4000 watts, but the exact power capacity depends on the power factor (typically around 0.8 for UPS systems). Battery Backup: Ensures that connected equipment continues to run during power outages. The runtime depends on the load being connected and the battery capacity. Surge Protection: Provides protection against voltage spikes and surges, which can damage sensitive equipment. Voltage Regulation: The UPS can regulate incoming voltage to ensure connected devices receive consistent, safe power even if the input voltage fluctuates. Compact Design: These units are usually compact and designed to fit into standard server racks or other equipment areas. Advanced Features: Some Vertiv 5kVA models come with monitoring and management capabilities via network cards, allowing you to check the status, set alarms, or configure settings remotely. Scalability: Many Vertiv UPS systems are modular and can be expanded with additional battery packs or additional units if needed. Maintenance Bypass: Ensures continuous operation and simplifies service and maintenance tasks.

The Liebert APM is a modular, scalable, and flexible Uninterruptible Power Supply (UPS) system from Vertiv (formerly Emerson Network Power). It's designed to provide reliable power protection for a wide range of applications, including IT, industrial, healthcare, and telecommunication environments. The Liebert APM series comes in various power ratings, with the range you mentioned being 30 kW - 300 kW, as well as the smaller 1 to 25 kVA units, offering high flexibility for different power requirements. Key Features of the Liebert APM Series: Modular Design: One of the standout features of the Liebert APM UPS system is its modular design. This allows users to scale the system based on their current needs and future expansion. The modular units can be added incrementally, making it highly adaptable. This modular approach allows for easy maintenance and upgrades without having to replace the entire UPS unit. High Efficiency: The Liebert APM delivers high efficiency, typically achieving up to 95% or more under normal operating conditions. This efficiency helps reduce operational costs and energy consumption. It also features Eco-mode operation, which optimizes energy savings when operating in non-critical situations without compromising protection. Compact and Flexible: Despite its modular nature, the Liebert APM system has a compact design that fits easily into most data centers and industrial setups, where space can often be at a premium. It can be configured for 1-phase or 3-phase power supply, offering flexibility for different types of loads and systems. Scalable Power: The Liebert APM is available in a range from 1 kVA to 300 kVA, which makes it suitable for small server rooms to large data centers. The system allows for easy scalability by adding additional power modules as needed to meet growing demands. Flexible Battery Configurations: The UPS system supports a variety of battery configurations, allowing for customization based on your runtime requirements. You can select from different battery types, including VRLA (Valve-Regulated Lead-Acid) and lithium-ion batteries. Advanced Monitoring and Management: Liebert APM comes with Intelligent Monitoring that provides real-time data on the UPS’s performance, such as input/output voltage, battery status, and efficiency. It supports both local and remote monitoring, ensuring that technicians can be alerted to issues before they become critical problems. The system can be integrated with network management systems (NMS) for centralized control across multiple units. Dual Input Capability: Some models of the Liebert APM offer dual input power sources, providing redundancy for critical applications. This feature ensures that the system remains operational even if one power input fails. Fast Response Time: The Liebert APM offers a fast transfer time (typically in the milliseconds), ensuring that sensitive equipment is protected even during brief power outages or voltage fluctuations. Applications: Data Centers: Providing reliable, scalable power protection for server rooms and IT infrastructure. Industrial: Protecting critical manufacturing equipment and automated systems from power interruptions. Healthcare: Ensuring medical equipment, including imaging devices, lab instruments, and patient monitoring systems, remain operational during power outages. Telecommunications: Keeping communication systems up and running to ensure continuous operation of vital network infrastructure. Benefits: Scalability: The ability to scale up or down as required, which is a huge benefit for growing businesses or changing environments. Reduced Total Cost of Ownership (TCO): With high efficiency and modularity, the Liebert APM reduces energy consumption and minimizes the cost of maintenance. Reliability: Known for providing excellent protection against power issues, including surges, spikes, and outages. Customization: Supports different configurations and battery options to meet specific needs, offering flexibility across various industries. Models & Power Ratings: Small Power Ratings: For smaller environments or edge computing setups, Liebert APM models ranging from 1 kVA to 25 kVA offer robust protection without being overly complex. Large Power Ratings: For larger industrial or data center applications, the 30 kW to 300 kW versions provide scalable power protection to ensure high availability for critical operations.

The Vertiv 60 kVA Online UPS is an uninterruptible power supply (UPS) designed to provide reliable and continuous power to critical equipment in case of power interruptions. Here are some key details and features typically associated with this kind of UPS: Key Features: Online UPS Technology: The Vertiv 60 kVA UPS uses online double-conversion technology, meaning it provides constant, clean, and stable power to connected equipment by continuously converting incoming AC power to DC and then back to AC. High Capacity: With a capacity of 60 kVA (kilo volt-amperes), this UPS is ideal for medium to large-sized businesses or industrial applications that require a significant amount of power protection, such as data centers, manufacturing equipment, or IT infrastructure. Energy Efficiency: These systems are typically designed to offer high efficiency, reducing operational costs while maintaining reliable performance. Some models offer "eco-mode" functionality to optimize efficiency during non-critical times. Battery Management: Vertiv UPS units generally feature advanced battery management technology that ensures longer battery life, more efficient charging, and optimal performance. The batteries are usually hot-swappable, allowing for maintenance without shutting down the system. Compact Design: Despite its high capacity, the Vertiv 60 kVA Online UPS is designed to have a relatively compact form factor, making it easier to integrate into limited spaces in data centers or industrial settings. Communication and Monitoring: Many Vertiv UPS systems come equipped with intelligent monitoring systems that allow users to track performance, status, and any faults. This can often be done remotely through a web interface or software. Bypass Capability: Some models offer an internal bypass, which allows the load to continue operating even during maintenance or if the UPS needs to be shut down for any reason. Typical Applications: Data Centers: Ensuring that critical server equipment continues running during power interruptions. Industrial Automation: Protecting machinery and control systems from voltage sags or outages. Healthcare: Protecting medical equipment that is sensitive to power fluctuations. Telecommunications: Ensuring consistent power supply to communication infrastructure. Advantages: Continuous Power Protection: Ideal for environments where power outages can cause data loss, downtime, or even equipment damage. Scalability: Can be paired with additional units or battery banks for higher power requirements. Reliability: The Vertiv brand is well-regarded in the power protection industry for producing durable and dependable UPS systems.

The HPL Lithium-Ion Battery Energy Storage System is a type of energy storage technology that uses lithium-ion batteries to store and manage electrical energy. These systems are typically used to store excess energy generated from renewable sources like solar and wind or from the grid, and release it when needed to help stabilize energy supply and demand. Here’s a breakdown of the key components and features that are generally associated with Lithium-Ion Battery Energy Storage Systems (BESS), including those from HPL or similar manufacturers: Key Features: Lithium-Ion Technology: Lithium-ion batteries are favored for their high energy density, long cycle life, and efficient performance. They are commonly used in applications like electric vehicles, grid storage, and consumer electronics. Energy Storage: These systems store electrical energy in lithium-ion battery packs and release it during periods of high demand, or when renewable energy production is low (e.g., on cloudy days for solar energy systems). Efficiency: Lithium-ion batteries typically offer high efficiency in terms of energy conversion, with round-trip efficiencies often exceeding 90%. This means that most of the stored energy is usable when discharged. Modular Design: HPL and other manufacturers often design their battery systems with modularity in mind. This means that the system can be scaled to fit a variety of needs, from residential to commercial and industrial applications. Grid Integration: These energy storage systems are commonly integrated with the electrical grid. They can help balance grid frequency and voltage, provide backup power during outages, and support the integration of renewable energy sources by smoothing fluctuations in supply. Battery Management System (BMS): The BMS ensures the safety, performance, and longevity of the battery by monitoring the state of charge (SOC), temperature, and other critical parameters. It can also prevent overcharging, over-discharging, and overheating. Applications: Residential Use: Homeowners can use these systems to store solar energy for use during the night or power outages. Commercial & Industrial Use: Businesses can use these systems to reduce demand charges or to provide backup power. Grid-Scale: Large energy storage systems can be used to stabilize the grid and facilitate the integration of renewable energy at a larger scale. Advantages: Sustainability: By storing renewable energy, these systems contribute to reducing carbon footprints and dependence on fossil fuels. Flexibility: They can be used in a wide range of applications, including residential, commercial, and large-scale energy storage. Cost Savings: Especially in commercial applications, they can help reduce energy costs by managing peak demand and reducing reliance on expensive grid power during peak periods.

The Amaron Quanta 12V 18Ah is a type of sealed lead-acid (SLA) battery, commonly used for backup power applications, such as in UPS systems, inverters, and other critical power supply systems. Here's a detailed breakdown of its specifications and features: 1. General Overview Brand: Amaron Quanta Battery Type: Sealed Lead-Acid (SLA) Battery Voltage: 12 Volts (V) Capacity: 18 Ampere-Hours (Ah) 2. Key Features Longer Battery Life: Amaron Quanta batteries are designed for long-lasting performance and high reliability. They typically offer a good lifespan, especially in applications with a low depth of discharge (DOD). Maintenance-Free: The battery is sealed, so it doesn’t require regular maintenance (e.g., adding water). Vibration Resistance: These batteries are designed to withstand vibrations, making them ideal for use in environments like telecoms, solar power, and UPS systems. Wide Operating Temperature: They can operate in a wide range of temperatures, typically from 0°C to 40°C, making them versatile for use in different climates. 3. Technical Specifications Voltage: 12V (Nominal) Capacity: 18Ah (Ampere-Hours) Dimensions: Length: 181 mm Width: 77 mm Height: 167 mm Weight: Around 5.2 to 5.5 kg (varies slightly based on exact model) Charge Voltage: 14.4V to 15.0V (during charging) Discharge Voltage: Typically 10.5V to 11.0V for complete discharge Self-discharge: Less than 3% per month at 25°C 4. Applications UPS Systems: The 12V 18Ah battery is widely used in smaller uninterruptible power supplies (UPS) for providing backup power to sensitive electronics. Inverters: It can also be used in small-scale inverters to provide backup power to homes or offices. Telecommunications: In telecom applications, these batteries can be used for backup power to critical network equipment. Solar Energy Storage: Sometimes used in small-scale solar energy systems for storing energy for use during off-sunlight hours. 5. Battery Design Features Valve Regulated Lead-Acid (VRLA): The Amaron Quanta battery uses VRLA technology, which means the battery is sealed and uses a valve to release gas in case of overpressure. Deep Cycle: Designed for regular deep discharge cycles, making it suitable for power backup applications where batteries frequently discharge. Absorbent Glass Mat (AGM): Some models use AGM technology, where the electrolyte is absorbed in a fiberglass mat, allowing the battery to be spill-proof and leak-proof. 6. Charge/Discharge Characteristics Charging: Amaron Quanta batteries typically use a constant voltage charge, with a float charge voltage of around 13.5V to 13.8V. Discharge: The battery can typically discharge down to around 10.5V under load, but frequent deep discharges can reduce the battery's overall lifespan. 7. Advantages Longer Service Life: Typically offers a long life when maintained and used properly, making it a cost-effective option for long-term use. Reliable Performance: Known for reliability in maintaining charge over time, especially in demanding environments. Environmentally Friendly: Sealed and maintenance-free design minimizes risks associated with acid leakage and spills. 8. Maintenance Maintenance-Free Design: As mentioned, the battery is sealed, so it doesn't require regular maintenance like adding distilled water. However, regular inspection for corrosion on terminals and proper charge maintenance is recommended. Charging Recommendations: Always charge the battery in accordance with the manufacturer’s recommendations. Overcharging or undercharging can significantly reduce the battery’s lifespan. 9. Warranty Amaron Quanta batteries often come with a warranty that covers defects in material or workmanship, which typically lasts for 1 to 2 years depending on the seller and country-specific terms. 10. Compatibility Compatible Devices: The Amaron Quanta 12V 18Ah battery is commonly used in small UPS systems, solar power applications, and other critical systems where consistent backup power is required. Charging Systems: Can be used with most standard 12V chargers designed for SLA or AGM batteries. Conclusion The Amaron Quanta 12V 18Ah battery is an ideal solution for users looking for a reliable, low-maintenance, and efficient power backup option in smaller systems. It is widely used in UPS systems, inverters, and telecommunications applications where it can provide critical backup power when needed.