FAQ

Below are some of the more common questions we get asked - but please don't hesitate to call if there is anything you would like to know.

Q. Some UPS manufacturers give the autonomy time at full load but others give it at typical load. What is the difference?

A. The "full load" time is the minimum autonomy time you can expect if the UPS is at maximum load however it is more interesting to know the time you can expect when the UPS is running at a typical load. To run the UPS effectively and efficiently it is best to aim for the load to be around 75 to 80% of the maximum rating. For instance if your load is 1600VA then a 2000VA sized UPS would be a good size to choose. Also to be considered is if you think the load may increase in time, possible by a new more powerful computer or by the addition of other equipment, therefore size the UPS to allow for possible future expansion.

Q. What do I look for when choosing a PDU?

A. It is often necessary to connect a number of loads to one ups. The PDU (Power Distribution Unit) fulfils that requirement.

There are a number of things to be considered - First:

1. Where will you install the PDU? Will it be horizontally across the back of a rack or vertically on one side of the rear of the rack? Will you need two vertical PDU's (both RH and LH) to feed dual power supplies in your computers?

2. Where will the supply for the PDU come from? Will it be a 13A socket or from a 10A or 16A IEC socket on the back of a UPS or even from a 16A or 32A Commando Socket?

Next: What kind of outlets do you need - do your loads have 13A plugs or 10A or 16A IEC plugs?

If you choose IEC socket outlets do you want them individually fused?

Do you want to avoid plugs being accidentally pulled out? If so choose locking plugs and sockets.

Once all this is decided choose your PDU from the appropriate catagory.

If in doubt please give us a call!

Q. What is a "Maintenance Bypass Switch" and do I need one?

A. A Maintenance Bypass Switch is a recommended option where the computer system must run continuously without being shut down.

The UPS sits between the Utility Power Supply and the computer. Should the UPS fail it has an internal electronic bypass which continues to supply the utility power to the computer; however, to repair the UPS it has to be shut down and made safe so the computer also has to be shut down to do that.

A Maintenance Bypass is external to the UPS and is connected in such a way that the faulty UPS can be repaired, even disconnected, without shutting down the computer.

Q. How do I dispose of Scrap batteries or UPS?

A. Lead Acid batteries of the type used in UPS, security and fire alarm systems are classed as hazardous waste and must be disposed of in accordance with strict environmental regulations. Advanced Power Care can arrange this for you and provide the correct Environment Agency consignment note which you will need to keep for a period of time to confirm that you have disposed of the waste correctly.

Q. How do I get the correct size of UPS for my computer equipment?

A. For individual computers check the rating plates attached of computer, VDU and any peripheral equipment to be attached to the UPS, add together the power consumptions and size the UPS about 20% larger to allow for inrush currents.

This also applies to larger networks but to be more accurate it may be worth recording the power being used by the equipment to be protected. This may be less expensive than purchasing a UPS which is far larger than necessary and which will run inefficiently.

Q. Should I connect my printer to the UPS?

A. The main use of the UPS is to continue to supply electrical power to the computer/network when the utility power supply experiences disturbances or outages. This means that data on the computer system is protected until power is restored or the computer is shut down in an orderly fashion. It is not normally a problem if power is lost to a printer as it is unlikely that the printer will be in use at the time of the outage and, even if it is, it is unlikely that any data loss or damage would occur. Printers also often take heavy current surges from the supply so are best not connected to the UPS. There are applications where printers are involved in long print runs and therefore need to be supplied by the UPS. In these cases it is essential to size the UPS appropriately and consideration should be given to the autonomy time available.

Q. When trying to work out the size of UPS needed what is Power Factor?

A. Induction or capacitance in AC circuits causes the voltage and current not to be synchronised; therefore the Volt/Amps (VA) and Watts used are at different levels. This difference is the Power Factor. The watts rating is always less than the VA. It is not necessary to understand this in detail; just remember when sizing the UPS not to exceed either the watts or the VA rating.

Q. How should I look after my UPS/batteries?

A. Batteries are particularly susceptible to high temperatures. The batteries in single phase UPS are generally standard commercial batteries which have a design life of 3 to 5 years at 20 degrees C. However, if the temperature is high, say 30 degrees C, the life expectancy is halved. So it is very important to locate the UPS and batteries in a clean, dry, well ventilated environment not close to radiators or other heat sources. Remember that the sun shining on the UPS through a window can raise its temperature considerably.

Q. UPS seem to have only a few minutes back up time. What happens in the case of long utility outages?

A. Yes, standard UPS systems usually have autonomy times of just a few minutes.

Utility power failures generally fall into two types:

1. Very short disturbances or outages caused by "cable slap" during storms or power switching problems. The UPS will carry the load through these very short outages.

2. Long outages caused, say, by cutting a power cable during construction work or a fire in a substation transformer. The UPS will detect if the outage is long and give an alarm to tell the user to shut down the computer before the autonomy time ends, so saving data. This can also be done automatically using PowerShield software. To avoid the necessity of shutting down the computer extra battery packs can be employed to extend the autonomy time. At large computer sites it is standard to install generators which start automatically in the case of utility power failure to restore the power feed to the UPS.

Facts about Batteries

The batteries offered in this shop are all VRLA (Valve Regulated Lead Acid)

There are different types of VRLA battery depending on the application and it is important to use the correct type to achieve the best performance and longest life.

  • Float charge - this is where the battery sits constantly on charge and may be infrequently discharged. Applications are UPS, Emergency Lighting and Security systems. Charge voltages should be 6.75 volts for a 6 volt battery and 13.5 volts for a 12 volt battery. Suitable Yuasa batteries for these applications are NP, NPL, SWL and EN ranges
  • Cyclic use - this is where the battery is constantly charged and discharged. Applications are Wheel Chairs, Golf Trolleys, portable equipment. Charge voltages can be higher to achieve fast recharge at 7.2 volts for a 6 volt battery and 14.4 volts for a 12 volt battery but must not be left continually connected or the battery will be destroyed by overcharging.Yuasa NPC batteries are designed for these applications

Battery Care

  • Temperature - The normal operating temperature for VRLA batteries is 20°C to 25°C. Operating the battery consistently at temperatures higher than this can considerably reduce its life expectancy.
  • Overcharge - Excessive charge voltages may cause heat, gas discharge and plate corrosion therefore reducing battery life.
  • Undercharge - Continual undercharging will cause sulphation which will reduce battery capacity. If discovered early it may be possible to remove the sulphation by using a higher charge rate for a short period but if sulphation exists for some time it may be difficult or impossible to remove.

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