Modern data centers require a careful approach to power supply. It is necessary to simultaneously monitor the status of loads and manage the connection of equipment. This can be done using cabinets, modules, or power distribution units. About what type of power equipment is best suited for specific situations, we talk in our post on examples of Delta solutions.
Powering a dynamic data center is often a daunting task. Additional devices in racks, the transition of equipment to sleep mode or, conversely, an increase in load lead to an imbalance in the power supply, an increase in reactive power and suboptimal operation of the electrical network. Power distribution systems help to avoid losses, ensure the efficient operation of equipment and protect it from possible power supply problems.
When designing power networks, IT professionals often face a choice between cabinets, modules, and power distribution units. Indeed, in essence, all three categories of devices solve the same tasks, but at different levels and with a different set of options.
Power Distribution Cabinet
A power distribution cabinet, or PDC (power distribution cabinet), is a top-level power control device. The cabinet allows you to balance the power supply for dozens of racks in the data center, and the use of several cabinets at once makes it possible to control the operation of large data centers. For example, such solutions are used by cellular operators - it took more than 5000 power distribution cabinets to power a data center for 50 racks, in Shanghai.
The Delta InfraSuite PDC, which is the same size as a standard 19-inch cabinet, contains two groups of single-pole circuit breakers protected by auxiliary switches. The cabinet can control the current parameters of each circuit with a separate switch. The power distribution cabinet has a built-in alarm system for uneven load sharing. As an option, Delta cabinets are equipped with additional transformers for generating various output voltages, as well as modules for protection against impulse noise, such as those created by lightning discharges.
For management, you can use the built-in LCD display, as well as external energy management systems connected via the RS232 serial interface or via SNMP. The device is connected to the external network through a special InsightPower module. It allows you to send alerts, control panel data and distribution network status parameters to a central server. This is the main component that enables remote management and monitoring, and notifies system engineers of critical events via SNMP traps and email.
Data center specialists can find out which phase is loaded more than others, and switch some consumers to a less loaded one or schedule the installation of additional equipment in a timely manner. On the screen, you can monitor parameters such as temperature, earth leakage current, the presence or absence of voltage balance. The system has a built-in log that stores up to 500 cabinet event records, which allows you to restore the desired configuration or analyze errors that preceded the emergency shutdown.
In the Delta range, the PDC is connected to a three-phase network and can operate at 220 V with a deviation of no more than 15%. The range includes models with a capacity of 80 kVA and 125 kVA.
Power Distribution Modules
If the power distribution cabinet is a separate cabinet that can be moved around the data center in case of redevelopment or changes in the location of the load, then modular systems allow you to place similar equipment directly in the racks. They are called RPDC (Rack Power Distribution Cabinet) and are small distribution cabinets that occupy 4U in a standard rack. Similar solutions are used by Internet companies that require guaranteed operation of a small fleet of equipment. For example, distribution modules were installed as part of a comprehensive data center security solution Germany.
If we talk about Delta equipment, the power of one unit of RPDC can be 30, 50 or 80 kVA. Multiple modules can be installed in a single rack to power all loads in a small data center, or one RPDC can be placed in different racks. The latter option is suitable for powering sufficiently powerful servers that need power control and redistribution of power depending on the configuration and load.
The advantage of a modular system can be considered the ability to increase capacity as the data center grows and scales. Users often opt for RPDC when a full cabinet creates too much headroom for their current 2-3 rack configuration.
Each module is equipped with a touch screen with almost the same control capabilities as a separate PDC, and also supports RS-232 interfaces and smart cards for remote control. Distribution modules monitor the current in each of the connected circuits, automatically inform about abnormal situations and support hot swapping of switching devices. System status data is recorded in the event log, which can store up to 2 entries.
Power Distribution Units
Power distribution units are the most compact and cost-effective systems in their category. They allow you to monitor the operation of equipment within a single rack, providing information about the state of the lines and the load. For example, such blocks were used to equip Β» in St. Petersburg and consortium "Digital Enterprise" in Chelyabinsk.
Blocks come in different formats, however, models made using Zero-U technology are placed in the same rack as the main equipment, but do not occupy separate βunitsβ - they are mounted vertically or horizontally on structural elements using special brackets. That is, if you use a 42U rack, after installing the unit, that is how many units you will have left. Each distribution block has its own signaling system: the presence of a load or an emergency situation on each of the outgoing lines is reported by LED indicators. Delta units have 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 into the rack, both in the standard Delta construct and in racks from other manufacturers. This is possible due to the universal set of brackets. Power distribution units can be installed vertically and horizontally, used when supplying electricity from single-phase and three-phase networks. The maximum current for Delta distribution blocks is 32 A, input voltage deviations are up to 10%. Connectors for connecting the load can be 6 or 12.
The main thing is to create a comprehensive management system
The choice between a cabinet, a block or a module depends on the load to be connected. Distribution cabinets are needed in large data centers, which, however, does not preclude the installation of additional modules or blocks for branching power to individual loads.
In medium-sized server rooms, one or two distribution modules are most often sufficient. The advantage of this solution is that the number of modules can be increased by scaling the power supply system along with the development of the data center.
Distribution units are usually installed in separate racks, which will be enough to equip a small server room. In the presence of a single control system, they also provide the ability to monitor and control energy consumption, but do not allow for dynamic redistribution of lines and hot swapping of contact elements and relays.
In modern data centers, you can simultaneously meet cabinets, modules, and power distribution units installed at different times and for different purposes. The main thing is to combine all equipment for power supply management into one monitoring system. It will allow you to control any deviations in power supply parameters and quickly take action: change equipment, expand capacity or move the 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