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Repair of UPS power modules

The power module is the main and rather expensive element of the UPS. Therefore, if a malfunction occurs, it makes sense to repair it, and not change it. In most cases, it is cheaper and faster – subject to the availability of the necessary competencies, tools and components.

In a broad sense, there can be two reasons for repairing:

  • planned or preventive maintenance, if the module is still working, but there are signs of imminent problems;
  • recovery after a malfunction if the module is out of order.

Each case has its own characteristics, which we will talk about.

Scheduled repair of the power module

The UPS Routine Maintenance Schedule includes a detailed examination of the power modules. In some cases, after maintenance, a recommendation is made to carry out repairs with the replacement of these components.

In what cases is scheduled maintenance necessary?

  • If the manufacturer’s recommended replacement period is appropriate.

For example, the service life of fans is on average 5 years – after this time they need to be replaced. 

  • If symptoms of malfunction are found. 

Sometimes the signs of incipient problems are clearly noticeable: the winding of the same fans may overheat, oil may leak from the bearings, and an uncharacteristic sound may be observed. Swelling, melting of the insulation, and a decrease in capacitance indicate a malfunction of the capacitors. However, the peculiarity of power blocks is that they include many electronic components, the degradation of which is often not visible. Experienced specialists can detect it using special measurements and comparing their results.

The decision on whether to carry out scheduled repairs remains with the owner of the data center. At the same time, it is important to understand that timely replacement of components that have exhausted their resource allows you to avoid serious problems that are always more expensive. A small malfunction develops unpredictably: it is accompanied by heating, burnout, local explosion, affecting other elements. The consequences can be of any scale – from severe damage to the module itself, with which it cannot be repaired, to the failure of the entire UPS. 

The maintenance procedure for the power module has features that we always warn the customer about. 

For maintenance, the module is taken out of service in order to clean and measure, then reconnect. Rarely, but it happens that after installation it fails to start. Sometimes customers interpret such a failure as a breakdown caused by the maintenance process itself. 

In fact, the opposite is true. The module has components that are only responsible for starting it. During operation, they are not involved, but after shutdown they perform their function: they conduct a self-test of the module, detect an existing malfunction and block the start. Thus, an incident is unpleasant, but useful: it reveals an existing problem, preventing it from growing to a critical level.

Emergency power module repair

If the equipment is serviced by a qualified service organization and undergoes routine maintenance on time, this allows you to control the degradation of components and not lead to accidents. 

However, maintenance is not always carried out with sufficient frequency and not every service partner is competent enough to notice all the hidden symptoms. In these cases, there is a possibility of sudden failure. The good news is that power modules are repairable in most cases.  

It should be borne in mind that the failure of one module often entails the breakdown of several neighboring ones. It happens like this: if there are five modules in the UPS and each of them is loaded by 80-90%, then the shutdown of one leads to an overload of the rest. The overload will not appear immediately, the entire system will work without obvious problems. But over time, due to the increased load, other modules will suffer.

That is why, in the event of an emergency, it is imperative to perform comprehensive diagnostics and repair of modules for the entire UPS. If you restore 1-2 modules and put them to those already damaged due to overload, we will get at least a rapid degradation of the repaired modules, as a maximum – a new accident. This will not happen due to poor repairs, but because the modules must have similar characteristics in order to properly distribute the load.

Another important requirement: in the event of an accident, it is highly undesirable to try to fix the breakdown on your own. A power module is a complex piece of equipment that requires highly specialized expertise to repair. After the intervention of an insufficiently experienced craftsman, it is much more difficult to accurately determine the malfunction and carry out repairs.

Stages and features of repair

Repair of power modules – both planned and emergency – is always carried out in a specially equipped repair area, at the customer’s site it is almost impossible. The only exception can be a complete replacement of the entire module or replacement of fans, which are simple procedures. 

In all other cases, detailed work with electronic components, boards, etc. is required, which requires a separate workplace with special conditions. These include a 3-phase input and load up to 25 kW, lighting and heat dissipation, a soldering station and a test bench. In addition, when turned on, load shedding is possible, which is not allowed in an operating data center.

The work includes several stages.

  1. Performing diagnostics

Scheduled repairs begin with maintenance on the UPS itself. If the need for additional diagnostics of a module is identified, it goes to our workshop. 

We also carry out full diagnostics in the case when the module arrives after a failure, with an already manifested malfunction. 

If you replace only one component without checking the rest, after some time a failure may occur in them, and the same module will be repaired again. Therefore, if potential problems are detected, we recommend eliminating all of them: a one-time full repair is safer and more profitable. 

  1. Coordination of the list of works

Based on the results of diagnostics, the list and cost of work is agreed with the customer. 

It is important to understand that we are only responsible for the serviceability of those components that we repair. If, after a month after replacing the inductance, the capacities, which the customer refused to work with, fail, this will not be a warranty case.  

  1. Debugg

Power module repair at the component level is a limited competence in the market and is carried out by only a few service organizations. 

Our engineers have full expertise and practical experience in this area. As the official service center of leading manufacturers, we take responsibility and carry out repairs under our own warranty.   

To speed up the process as much as possible, we keep a stock of the main components in our warehouse for replacement. This allows for a repair time of about 2-3 weeks. If a non-running element that is out of stock is out of order, we take over the delivery by ordering a replacement directly from the vendor.

In addition, we have a replacement fund: we can use spare parts from our modules to reduce the waiting time. It is also possible to provide a module for replacement during the repair period.

  1. Testing

After the repair is completed, the module is tested. We check it first at idle, then from the external network, from the battery, at load – in all operating modes. Each stage of testing takes 2-3 hours – you need to make sure that the module behaves correctly in all modes of operation for a long time.

Special equipment of the workshop is required for testing. First of all, this is the presence of a stand, which we assemble as a complete imitation of the UPS. In order to reliably test all possible modes of operation, the stand must provide the same characteristics as in the customer’s data center. It must also have one more power module for checking operation in parallel, a static bypass module for checking switching and transients. 

In addition, a loading machine is needed to check the module’s performance under load.¬†We load the power modules at 50-80% of the maximum load and keep it for a sufficient time to establish all temperature conditions.¬†

Stand examples

After the test results have confirmed that the module is fully functional, we return it to the customer.

So, in order to repair a module, a number of conditions are required:

  • high qualification level of specialists,
  • availability of modern equipment and stands,
  • availability of a workshop with special conditions,
  • available replacement components.

Meeting all these requirements, we carry out repairs of power modules with a high level of quality. This allows customers to save up to 70% of the budget compared to a complete replacement. 

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