Modern data centers require careful attention to power supply. It is essential to monitor load conditions and manage equipment connections simultaneously. This can be achieved using cabinets, modules, or power distribution units. We discuss which type of energy equipment is best suited for specific situations, using examples from Delta's solutions in our post.
Power supply for a dynamically evolving data center often proves to be a challenging task. Additional devices in racks, the transition of equipment to sleep mode, or, conversely, an increase in load can lead to power supply imbalance, a rise in reactive power, and suboptimal performance of the electrical network. Power distribution systems help avoid losses, ensure efficient operation of equipment, and protect it from potential power supply issues.
When designing power supply networks, IT specialists often face the choice between cabinets, modules, and power distribution units. Essentially, all three categories of devices address the same tasks, but at different levels and with varying options.
Power Distribution Cabinet
A power distribution cabinet, or PDC, is a high-level power management device. The cabinet allows for the balancing of power supply for dozens of racks in a data center, and using multiple cabinets enables the management of large data centers. For instance, mobile operators use such solutions — over 50 power distribution cabinets were required for the power supply of a data center with 5,000 racks. in Shanghai.
The Delta InfraSuite PDC cabinet, which matches the standard 19-inch rack dimensions, consists of two groups of single-pole circuit breakers protected by additional switches. The cabinet can monitor the current parameters of each circuit with individual switches. The power distribution cabinet features a built-in emergency alert system for uneven load distribution. As an option, Delta cabinets can be equipped with additional transformers to generate various output voltages, as well as surge protection modules, such as those created by lightning strikes.
Control can be done via the built-in LCD display, as well as external energy management systems connected through a serial RS232 interface or SNMP. Connecting the device to the external network occurs through a special InsightPower module. This allows alerts, control panel data, and distribution network status parameters to be transmitted to a central server. This is the main component that enables remote management and monitoring and alerts system engineers of critical events via SNMP traps and email.
Specialists servicing the data center can determine which phase is more loaded than others and switch some consumers to a less loaded phase or timely plan the installation of additional equipment. The screen can monitor parameters such as temperature, ground leakage current, and the presence or absence of voltage balance. The system includes a log that stores up to 500 event records from the cabinet, allowing restoration of the necessary configuration or analysis of errors preceding the emergency shutdown.
Regarding the Delta model line, the PDC connects to a three-phase network and can operate at a voltage of 220 V with a deviation of no more than 15%. The lineup includes models with capacities of 80 kVA and 125 kVA.
Power distribution modules
If the power distribution cabinet is a standalone unit that can be moved around the data center during reconfigurations or changes in load placement, then modular systems allow similar equipment to be placed directly in racks. These are called RPDC (Rack Power Distribution Cabinet) and represent small distribution cabinets occupying 4U in a standard rack. Such solutions are used by internet companies that require guaranteed operation of a small equipment fleet. For example, distribution modules were installed as part of a comprehensive solution for protecting the data center. in Germany.
Speaking of Delta equipment, the power of a single RPDC unit can be 30, 50, or 80 kVA. Multiple modules can be installed in one rack to supply power to all loads of a small data center, or one RPDC can be placed in different racks. The latter option is suitable for powering fairly powerful servers that require energy supply control and power redistribution based on configuration and load.
A plus of the modular system is the ability to scale power as the data center grows. Users often prefer RPDC when a full cabinet provides too much capacity for the current configuration of 2-3 racks of equipment.
Each module comes equipped with a touchscreen that offers nearly the same control capabilities as a standalone PDC, and also supports RS-232 interfaces and smart cards for remote management. Distribution modules monitor the current in each connected circuit, automatically notify about abnormal situations, and support hot-swapping of switching devices. System status data is logged in an event log that can store up to 2,000 entries.
Power distribution units
Power distribution units are the most compact and economical systems in this category. They allow monitoring of equipment operation within a single rack, providing information on line status and load. For example, such units were used to equip in Saint Petersburg and of the consortium 'Digital Enterprise' in Chelyabinsk.
Power distribution units come in various formats, but models designed using Zero-U technology are mounted in the same rack as the main equipment without occupying separate 'units' – they are securely attached either vertically or horizontally to the structural elements using special brackets. This means that if you are using a 42U rack, after installing the unit, you will have exactly that many units left. Each distribution unit has its own signaling system: LEDs indicate load presence or irregular situations on each outgoing line. Delta units feature an RS232 interface and connect to monitoring systems via SNMP, just like cabinets and power distribution modules.
Measuring and basic distribution units can be installed directly in the rack, in both the standard Delta design and in racks from other manufacturers. This is possible due to a universal set of brackets. Power distribution units can be installed vertically or horizontally and can be used with single-phase and three-phase power supplies. The maximum current for Delta distribution units is 32 A, with input voltage deviations of up to 10%. There can be either 6 or 12 load connection sockets.
The key is to create a comprehensive management system
The choice between a cabinet, unit, or module depends on the specific load that needs to be connected. Large data centers require distribution cabinets, although this does not preclude the installation of additional modules or units for branching power to individual loads.
In medium-sized server rooms, one or two distribution modules are often sufficient. The advantage of this solution is that the number of modules can be increased, scaling the power system along with the development of the data center.
Distribution units are typically installed in specific racks, sufficient for equipping a small server room. When there is a unified management system, they also allow for monitoring and control of energy consumption, but do not enable dynamic redistribution of lines or hot swapping of contact elements and relays.
Modern data centers can simultaneously feature cabinets, modules, and distribution units installed at different times and for different purposes. The key is to integrate all equipment for power management into a single monitoring system. This will allow control over any deviations in power supply parameters and prompt action: changing equipment, expanding capacity, or shifting load to other lines/phases. This can be done through software such as Delta InfraSuite or a similar product.
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Source: habr.com
