An uninterrupted power supply is important both for a single machine at an industrial enterprise, and for a large production complex as a whole. Modern energy systems are quite complex and reliable, but they do not always cope with this task. What types of UPS are used for industrial facilities? What requirements do they have to meet? And are there any special operating conditions for such equipment?
Requirements for industrial UPS
Given the purpose, we can highlight the main characteristics that uninterruptible power supplies for industrial facilities should have:
- High output power. It is determined by the capacity of the equipment used in enterprises.
- Maximum reliability. It is laid down at the stage of developing the design of sources. In their manufacture, components are used that make it possible to repeatedly increase the reliability of devices. This, of course, increases the cost of the UPS, but at the same time increases the service life of both the sources themselves and the equipment they provide with electricity.
- Thoughtful design that facilitates diagnostics, maintenance and repair of uninterruptible power supplies. This approach provides easy access to all units of the system and minimizes the time required to disassemble or replace UPS components.
- Possibility of scaling and smooth increase of power. This is necessary when the demand for power increases.
Types of industrial UPS
For industrial purposes, three main types of uninterruptible power supplies are used:
- Reserve (in other words Off-Line or Standby). Such sources are equipped with automatic switches, which, in the event of a power failure, switch the load to the batteries. These are simple and inexpensive systems, but they are not equipped with mains voltage stabilizers (which means that the batteries wear out faster) and take a certain time to switch power to the batteries (about 4 ms). Such UPSs can only cope with short-term power outages and are used to service non-critical production equipment.
- Line-interactive (Line-interactive). Such sources are equipped with transformers to stabilize the output voltage. This reduces the number of load transfers to the batteries and saves battery life. At the same time, UPSs are not designed to filter interference and control the shape of the voltage. They are optimal for uninterrupted power supply of equipment, for which only the value of the input voltage is important.
- Online (On-Line). In such sources, double voltage conversion occurs. First, from AC to DC (it is supplied to batteries), and then back to AC, which is used to power industrial equipment. In this case, not only the magnitude of the voltage is clearly controlled, but also the phase, frequency and amplitude of the alternating current. Some manufacturers use bidirectional inverters instead of double conversion, which alternately perform the functions of a rectifier or inverter. Online UPSs save energy and are more efficient. Such sources are suitable for protecting powerful and network-sensitive equipment.
In addition, industrial UPS can be divided into two groups depending on the type of load being fed:
- The first includes uninterruptible power supplies, which are used to protect against interruptions in the power supply of production processes and work equipment. For this purpose, UPSs of a redundant or line-interactive type can be used.
- To the second - UPS, which are used for uninterrupted power supply of IT infrastructure: data storage systems or servers. On-Line type sources are suitable for this.
Operating conditions for industrial UPS
Enterprises of different industries have their own specifics, which means that different requirements are imposed on uninterruptible power supplies. In fact, each such project is unique and needs to be optimized for its equipment. Here are just a few examples of production specifics:
- The UPS used at refineries to ensure the safe operation of distillation columns are used for emergency power supply not only for control systems, but also for actuators. Accordingly, they must have high power.
- Geothermal power plants emit a by-product: sulfur dioxide gas. On contact with atmospheric moisture, it forms sulfuric acid vapors. It is able to quickly destroy the materials that are used to make uninterruptible power supplies.
- On offshore oil platforms, another danger is high humidity, salt and the possibility of horizontal or vertical movements of the base on which the UPS is installed.
- Steel mills have strong electromagnetic fields that can cause interference and cause circuit breakers to trip.
This list could be expanded with dozens of other examples. At the same time, regardless of the specifics of an industrial enterprise, uninterruptible power supplies require reliable operation for 15–25 years. We can distinguish two main factors that affect the operation of the UPS:
- Accommodation. Sources are strictly not recommended to be placed near energy consumers. They must be protected from high temperatures, polluted air or mechanical influences. For UPS, the optimum temperature is 20–25 °C, but they continue to work properly at temperatures up to 45 °C. Increasing it further shortens the life of the batteries, because all the chemical processes in them are accelerated.
Dusty air is also harmful. Fine dust plays the role of an abrasive and leads to wear of the working surfaces of fans and failure of their bearings. You can try to use UPS without fans, but it is much more reliable to initially protect them from such influences. To do this, the equipment must be placed in a separate room with a maintained temperature regime and clean air.
- Energy recovery. The very idea of returning part of the electricity to the grid and reusing it is certainly useful. It allows you to reduce energy costs. Recovery systems are actively used, for example, in railway transport, but they are harmful for uninterruptible power supplies. When using reverse energy, the voltage on the DC bus increases. As a result, the protection is activated and the UPS goes into bypass mode. It is impossible to completely exclude the consequences of recovery. They can only be minimized by using transformer uninterruptible power supplies.
Source: habr.com