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Chapter 13: Upgrading UPSs, Monitoring the System, and Choosing Service Tools
About This ChapterThe past several chapters have talked about upgrading the hardware within a server. This chapter finishes our discussion of upgrades by talking about upgrading the external equipment that most professionals forget about: the UPSs. It also describes the various software and hardware approaches to system monitoring. Finally, it lists a number of service tools that may help you maintain your existing systems and identify when an upgrade is necessary.
The lessons in this chapter will prepare you for the next few chapters, which focus on proactive maintenance of the system.
Before You BeginTo complete this chapter, you should have
- Your server documentation
- Any batteries or UPSs necessary to replace existing batteries and UPSs
Lesson 1: Upgrading UPSsThis lesson discusses the various ways of upgrading a UPS, including replacing existing batteries and adding new batteries to increase run time. It also discusses matrixed UPSs and how to upgrade the inverter units in addition to the batteries.
After this lesson, you will be able to
- Add or replace batteries on a UPS
- Install new inverter units on matrixed UPSs
Estimated lesson time: 20 minutes
Replacing UPS BatteriesUPS batteries have a fixed useful life, after which they are unable to provide the power the UPS inverter needs to support the attached load. Thus, all batteries eventually need to be replaced. Battery life is generally listed with the UPS but can range from 18 months to 5 years, depending upon the type, size, and usage of the battery. As you learned in Chapter 2, Lesson 2, there are three types of UPSs. The small UPSs have fixed batteries that aren't replaceable. In these UPSs, you must replace the UPS itself at the end of the batteries' life span. Mid-sized UPS have replaceable internal batteries, and large UPSs have external battery racks that house replaceable batteries.
This discussion focuses first on the mid-size UPSs that have replaceable batteries. Unless you have a large environment, you're likely to have this type of UPS, with batteries housed inside the unit.
Replacing a Battery in a Mid-Sized UPS
The primary challenge when replacing a battery in a mid-sized UPS is that you have to open the unit itself up to do so. In most cases, the UPS manufacturer will indicate that the unit is designed to allow hot swapping of the battery. That is, the UPS (and the servers it supports) need not be shut down to replace the battery.
However, the manufacturer will also generally include some strong cautions about doing a hot-swap upgrade because of the high voltages present inside the UPS. These cautions should be sufficient to convince you that it's best to plan to replace the UPS battery during scheduled maintenance. The risk of personal injury and the possibility that the UPS might shut down during this process are substantial enough to warrant replacing the battery while the connected servers are shut down.
Mid-sized UPSs use sealed lead-acid batteries similar to the ones used in cars. Unlike some car batteries, however, UPS batteries are completely maintenance free. The fact that these batteries are sealed helps ensure that no harmful acid leaks out inside the battery case.
The materials used in the construction of lead-acid batteries are harmful to the environment. Most UPS manufacturers will recycle old batteries for you. Because it's illegal to dispose of these batteries yourself in most locations, we recommend that you take advantage of these recycling programs.
A general process for replacing the batteries in a UPS appears below. This procedure is for reference only. Due to the potentially dangerous voltages present inside a UPS, please refer to the battery replacement instructions for your specific equipment.
To replace the batteries in a UPS
- Shut down all servers and equipment connected to the UPS.
- Shut down the UPS.
- Unplug the UPS from the wall outlet.
- Remove the new battery from its packaging. (Save the packaging for returning the old battery.)
- Remove the front cover or case as indicated in the battery replacement guidelines.
- Remove the screws that hold the battery compartment door in place.
- Slide the battery forward until both wires connecting the battery to the UPS are visible.
- Disconnect the red, positive wire from the battery.
- Disconnect the black, negative wire from the battery.
- Slide the battery the rest of the way out.
- Slide the new battery in a little, leaving both terminals exposed.
- Connect the black, negative wire to the battery.
- Connect the red, positive wire to the battery.
- Ensure that no metal is exposed on the wire or the battery terminals.
- Push the battery completely into the battery compartment.
- Close and secure the battery door with the screws you removed earlier.
- Replace the UPS cover.
- Plug the UPS back into the wall outlet.
- Turn on the UPS, and ensure that the bad battery indicator is not lit. If the bad battery indicator is lit, call the UPS manufacturer or follow the troubleshooting procedures in the UPS user manual.
- Pack the old battery in the packaging you saved from the new battery, and seal it for return to the vendor's battery recycling program.
Even though power is disconnected from the wall, the batteries and circuitry in the UPS still contain significant electrical energy. You may want to remove metal rings and bracelets and be cautious of contact with bare wires.
As you can see, the process of installing a replacement battery in an existing unit is relatively trivial. The only significant issue involves the need to exercise caution because of the potentially high voltages remaining in the UPS.
Replacing a Battery in a Large UPS
Once UPSs reach a certain size, the inverterthe part that converts the battery power to alternating current (AC)is separated from the batteries. This separation allows you to replace the batteries without opening the inverter cabinet, helping to reduce the risk of shock when replacing batteries.
The size at which the inverter and batteries are separated varies by manufacturer and even by product line within a manufacturer. However, most of the time the change from internally sealed batteries to external batteries happens at around the 3 KVA threshold. UPSs that supply more than 3 KVA of power tend to have their inverter kept separate from the batteries, in part to keep the heat that the inverter generates away from the batteries, which don't respond well to heat.
For most larger UPSs, the procedure for replacing external batteries is simple. The following steps describe a typical UPS battery replacement when the UPS uses external battery packs supplied by the manufacturer. This type of arrangement is generally used in so-called matrixed UPSs (discussed in a later section) and in UPSs that are just large enough to warrant external battery cabinets but are too small to require a dedicated rack of batteries.
To replace a UPS battery when the UPS uses external battery packs supplied by the manufacturer
- Shut down the connected servers and devices (optional).
- Shut down the UPS (optional).
- Disconnect the battery cable from the UPS. You may have to remove a locking mechanism.
- If you're removing more than one battery pack, disconnect each battery pack from the others.
- Remove the battery pack(s).
- Place the new battery pack(s) next to the UPS.
- Connect the new battery pack(s) together, and lock the connectors in place (if a locking mechanism is provided).
- Connect the first battery pack to the UPS, and lock the connector in place.
- Verify that the battery failure indicator light on the UPS is off.
Larger UPSs require complete racks of batteries. Service technicians most often install these batteries to ensure that the wiring is done properly and that proper safety precautions are followed. If for some reason you decide to replace the batteries yourself, you'll follow a procedure similar to the following. As always, read the UPS documentation and follow the replacement instructions for the specific UPS.
To replace batteries in a large UPS
- Lock the UPS into line-conditioner-only mode, if possible. This will allow the UPS to continue using its transformers and MOVs to suppress power surges, along with preventing it from trying to transfer to battery power while the replacement is in progress.
- Disconnect the batteries from the UPS by removing the main connector from the UPS to the batteries.
- Disconnect each battery connecting cable, starting at the UPS and working backward. Place a protective plastic cap over the battery terminal after the cable is removed. Note the connection order, and be careful not to make contact between the positive lead of the battery and either the rack or a negative lead.
- Remove each used battery from the rack.
- Install each new battery into the rack.
- Individually connect each battery, starting with the battery farthest from the UPS and moving forward. Be careful not to touch any positive terminal or cable with any negative terminal, cable, or the rack itself.
- Once you've connected all of the individual cables, reconnect the battery racks to the UPS.
- Verify that the UPS sees valid batteries attached and that it doesn't indicate any kind of an error.
Adding New UPS BatteriesAdding new batteries to a UPS is very similar to replacing the batteries in a UPS. However, there are some very important differences. The first difference is that not every UPS supports extra batteries. In these cases, you are limited to the batteries the UPS already has.
The second difference involves the need to make sure that the battery cables can handle the current they will carry. When you're simply replacing batteries, you know that the connecting cables are sufficient to carry the current from the batteries to the inverter. When you're adding batteries to an existing configuration, however, you need to verify that the battery cables connecting the batteries to the inverter are sufficient to carry the current.
There are guidelines for the size of cable required for a given voltage and amperage, but the best idea is to contact the UPS manufacturer and verify that the cables are sufficiently sized for the additional batteries.
Working with Matrixed UPSsSomewhere in the middle ground between mid-sized and large UPSs exists a hybrid UPS that allows you to replace modules without taking down the entire system. These matrixed systems make expansion easy by allowing you to add inverter modules to support more load and battery modules to allow the load to be carried longer.
The fundamental difference between a matrixed UPS and a mid-sized UPS with replaceable batteries is that in a matrixed UPS the power generation and distribution components can be replaced independently. This means that it automatically supports a built-in fail-safe bypass mode of operation when the inverter is nonfunctional. In other words, the power will continue to be conditioned by the transformers and MOVs even if the inverter is not present.
This ability is certainly an advantage, but the sales of matrixed UPSs have not been significant, so similarly sized UPSs with replaceable batteries are usually a better deal than matrixed UPSs. (Due to economies of scale, devices that are sold in quantity are generally cheaper than those that cannot be made in similar quantities. This leads to matrixed UPSs being more expensive.)
Replacing an Entire UPSWith smaller to mid-sized UPSs, you're likely to just add a new UPS to handle new servers. However, if you have a large UPS, you'll generally replace it with a new, larger unit when you need to support greater loads. Using a single large UPS means that you have fewer units to monitor and maintain.
Replacing a large, hardwired UPS with a new one is a simple process. (Most large UPSs are hardwired into the electrical system of the building rather than being plugged in.) The new wiring is run for the new UPS, the supported systems are shut down, the old unit is shut down, the new unit is connected, and the new unit is started. The biggest catch to this whole procedure is the new wiring. Because the new UPS will support greater loads, it will require more power to run through it. As a result, the wires connecting the UPS to the outside utility and to the internal distribution panel often need to be upgraded. In addition, the internal distribution panel itself may need an upgrade. Take these electrical changes into account when you plan for the new UPS.