Original subtitles

The computer room needs to be at least 260 centimeters or 8.5 feet in height

The computer room needs to be at least 260 centimeters or 8 5 feet in height

measured from the top of the raised floor to the bottom of the suspended ceiling,

then additional height needs to be Icatered for in the computer room

then additional height needs to be catered for in the computer room

So, if you have a raised floor of forty centimeters,

the area above the suspended ceiling should be at least sixty centimeters,

but ideally, eighty centimeters in height

but ideally, eighty centimeters in height

but ideally eighty entimeters in height

If the raised floor is sixty centimeters,

the area above the suspended ceiling should be at least ninety centimeters,

you have learned that various standards apply to the raised access flooring system

and that the UK PSA MOB is one of the most often used standards

and that the UK PSA MOB is one lot the most often used standards

since floor tiles are a part of a raised floor, different floor loadings may apply,

such as uniform distributed loads, point loads or rolling loads.

such as uniform distributed loads point loads or rolling loads

being the raised floor, the computer room and the suspended ceiling,

and that appropriate clearance must be present below

Suspended ceilings create a nice-looking computer room environment

but it needs to be sized appropriately, and similar to the raised floor,

In the old days, light intensity used be measured in a unit called Lumen

Nowadays, the preferred measure of unit for light intensity is called Lux

or three feet above the floor level.

There are various standards available

which address the light infrastructure in buildings.

Ideally, therefore, you discuss with local consultants during the design phase,

| to understand in which category computer room should be classified,

that occupied spaces should have minimum light intensity of 500 Lux

This is quite a high level, which is to ensure a safe working environment

This is quite a high level, which is to ensure a safe working environment

will ensure you still have appropriate light within the back of the rack itself,

such as making connections to the equipment

by looking at the purpose of the room

and in practice, this is 50 to 100 Lux

Sufficient light levels must be present, 500 Lux in the horizontal plane,

demonstrates some of the better choices,

since for these light fixtures the fluorescent

tube is protected by a grill or plexiglass

The bottom illustration shows an example of an open light fixture,

which is certainly not recommended, due to the possible damage that may occur

to ensure that an equal level of light is available throughout all aisles

In some cases, where for example an office space is converted into a computer room,

it sometimes results in misalignment

Therefore, when you retrofit office area into a computer room,

Therefore, when you retrofit an office area into a computer room,

make sure that the contractor is realigning the light fixtures.

which is also feeding ICT equipment

Although it is tempting to make sure that there is always light in the data center,

The issue is that fluorescent lights create a lot of harmonic distortion.

The issue is that fluorescent lights create a lot of harmonic distortion,

will create a power qualrty disturbances

which could impact the connected ICT equipment

Therefore, lights must be connected to the raw supply of the building,

Therefore, lights must be connected to the raw supply of the building

and ideally, to the raw supply which is backed up by the standby generator

you need to make sure that the lights are connected to a dedicated UPS supply,

instead of the UPS that feeds the ICT equipment

It is important to realize that most regulations discussing emergency lights

it is important to realize that most regulations discussing emergency lights

and also higher intensity emergency lights

perhaps you have a few leftovers from that period in your life

and the most common types are displayed on this slide

The one at the too is sometimes referred to as "the headlight emergency light”,

This is certainly not a desirable. especially when you have many lights

and you will be shocked doing so yourself, finding out that plenty of these lights

This is achieved bv usina an EPS. which is short for Emergency Power Supply

This is achieved by using an EPS, which is short for Emergency Power Supply

high is short for Emergency Power Si

When the UPS has power on the input. it will also have power on the

only then the EPS will turn on the output,

In some cases.

In that case, the EPS will be configured similar to the UPS,

Lights should be adequately placed, taking into account potential obstructions,

When designing emergency lights

Studies from many hardware manufacturers Hand power consultants indicate

Studies from many hardware manufacturers and power consultants indicate

that the quality of power supply to computer rooms is not always appropriate

This may result in all sorts of problems, such as failures on equipment

Sometimes end-users spend a lot of time trying to diagnose why the equipment is failing

Unfortunately, a UPS is not able to address all potential power quality issues

| As a result, if the ground quality at the input of the UPS is of poor quality

as more ICT equipment is being deployed

B Nevertheless, the current trend is that jnsity in terms of power per square meter

which is the difference between the intake

This slide demonstrates a simplified overview on how power is being distributed

From this power generation plant, energy is distributed over transmission towers,

eight hundred thousand volts is stepped down to thirty three thousand volts

to avoid the stepping down of the voltage

This would commercially become unfeasible,

and therefore it is not an option either

to have a cost effective distribution

to have a cost effective distribution,

of how power is commonly distributed

from the incoming power supply to the computer room floor

from the incoming power supply to the computer room floor

from the incoming power supply to the computer room floor

we have left out details, such as breakers and electrical distribution boards,

we have left out details, such as breakers and electrical distribution boards

also called power distribution units,

which are shortly referred to as PDU

In case utility power becomes unavailable,

for whatever reason, the standby generator is present, which can take over

will detect this and start the generator

are connected to an ATS panel, the Automatic Transfer Switch.

or the emergency standby generator source

As mentioned during the previous slide,

the ATS panel will take power from either the utility power or the standby generator

If the utility input fails, it means you have to switch from normal to emergency

and moves to E to make a connection

before it makes the connection with E

Because of the break-before-make event, there will be a short moment

However, other load which is connected, such as air conditioners and lights,

might experience a small interruption of fifty to one hundred milliseconds

This may cause the lights to flicker and air conditioners to turn off and restart,

it is therefore recommended that air conditioners are configured

Looking at the ATS types, in the middle and the right hand side on the slide,

these are working on the same principle,

but instead of having a rotor switching from normal to emergency supply,

it is now achieved by using electromechanically activated breakers.

such as the ATS panel and the UPS

and during that time the UPS may need to be switched to the manual bypass mode

For this reason, some data centers implement a parallel configuration for the UPS

It means that the two UPS systems are operating concurrently,

Each UPS will take fifty percent capacity of the load inside the computer room

Should one of the UPS systems fail or taken out of service

due to maintenance, then the surviving UPS will take over the load

and the data center continues to operate with full power protection

such as a single generator serving as a backup to either source Aor B

It is possible that instead of having adundant UPS systems in each feed,

It is possible that instead of having redundant UPS systems in each feed,

the data center installs one UPS system,

based on the assumption that either A or B or both feeds are active

Since most ICT equipment is nowadays equipped with an A and B power supply,

However, there is still some equipment that only have one power supply

However, there is still some equipment that only have one power supply.

To avoid this issue, most data centers will deploy a static transfer switch,

but there is a fundamental difference between the ATS and STS,

which I will discuss on the next slide

This means that on the output of the STS there will be a break

This means that on the output of the STS there will be a break

However, this break is very short, this since an STS is based on power transistors,

An STS switches under twenty milliseconds.

With power transistors in place, you are able to switch so fast

With power transistors in place. you are able to switch so fast

With power transistors in place, you are able to switch so fast

that these curves allow a power interruption on ICT equipment of twenty milliseconds,

Anything more than twenty milliseconds may cause the ICT equipment to fail

STS panels can come as large units, feeding an entire computer room,

or a small rack mount unit, capable of switching power just for a single rack

Notice there are intelligent STS devices in the market

and if they are in sync, the system will perform a make-before-break

However, if the system measures that the A and B source are not in sync

to make sure that the two non-synchronous power sources are connected together,

Therefore, the principle of break before make is required

when operating non-synchronous sources.

The diagram on this slide represents another option for a dual feed setup,

The advantage of this setup is that each feed will always be on,

The advantage of this setup is hat each feed will always be on

since it will take power from either the main incoming feed or the alternative feed

the power feeds in the computer room would be in an A+B configuration

Depending on maintenance or a fault, the setup could automatically change to an A+A,

There is no need to pull a separate power cable for the single cord equipment,

As you can imagine, the cost to build and the cost to operate will increase.

in addition, where single powei luipment is still being used

and some high level redundancy options

it is commonly based on three phase power,

Commonly, the cables are colour coded,

The colour scheme varies by region or country, and in some cases even per timeline

and therefore multiple colour schemes are potentially available in a single building

This could lead to confusion. and even dangerous situations

if the people involved are not fully aware of the various colour coding schemes,

Licensed electricians should be familiar, so make sure qualified personnel

is working on your electrical installation

Therefore, you need to convert the incoming three phase power into single phase power

Be aware that in some countries, single phase power is based on two wires only

After the single phase breakers, you )mbine the ground and the neutral wire

As you can see. the so-called conversion from three phase to single phase

| There are five wires: the neutral, which is commonly black, the ground, which is green,

j To create a single phase using L1, it is combined with the neutral and the ground,

To create a single phase using L1, it is combined with the neutral and the ground

and you have created the single phase L2

At the incoming part of the PDU there is a three phase breaker installed

with each of them having single phase breakers serving one of the three phases

in order to create a single phase supply, to which you can connect the load

The output of the UPS is connected to he POU systems in the computer room,

will now be connected to either phase one,

and this means that each single phase should ideally cany the exact same load

which the computer room floor manager and his or her team need to take care of

which the computer room floor manager and his or her team need to take care of

From the UPS system, three phase cabling runs to the power distribution unit

also called the distribution board or DB

at this point three phase power is being converted to single phase power

The total load of the new ICT equipment is roughly 8 kilowatt

This will create a Imitation, since equipment installed in a particular rack row

It will therefore allow more flexibility to manage the data center.

It will therefore allow more flexibility to manage the data center

Connecting equipment can be done as such

but it wil help you to manage the data center for many years to come.

allowing you to balance the load between the phases within each rack itself

which is equipped with a dual power supply

Note there’s also equipment in the market which has three or even more power supplies

it is recommended to connect it to an STS,

What happens if it is the other way around

There are many ways to connect power to a rack

There are many ways to connect power to a rack.

This slide and the following slides will demonstrate some of the options

a Power Distribution Unit, and then onwards to the power rail of the rack

In this case, you have a single power rail, so many single points of failure

Even if dual power supply equipment is present,

such as in the bottom part of this rack,

Yes, it is possible to connect the second power supply to the power rail,

so that the equipment is at least protected from a power supply failure,

so that the equipment is at least protected from a power supply failure.

This slide shows a slightly better configuration,

In this option, there are two power rails

will be connected to either the left or the right hand side power rail

The dual power supply equipment can be connected to both power rails

due to, for example, a breaker trip.

the system will continue to operate

that although the system with the dual power supply is still operating,

it can no longer be used due to the loss of network connectivity

If there is any failure on the UPS

In this option, the computer room has two utility power feeds, indicated with A and B

This configuration wil significantly improve the redundancy,

since there is no longer a single point of failure, looking at the UPS,

the PDU and the utility power feeds

Since most of the equipment is based on a single power supply

it will, however, not contribute much to achieving high availability

there is still power in the rack, but since the majority of the equipment

In this case, both the utility A and B feed are connected to an STS

In this case, both the utility A and feed are connected to an STS

Should either the A or B feed fail

Realise that the STS is a single pint of failure in this configuration,

then all single-cord equipment that is connected will shut it down

then all single-cord equipment that is connected will shut it down

Some STS panels have a maintenance bypass, which can be activated,

so not really helpful for the availability of the equipment itself

the dual power supply equipment is also connected to the STS,

whereas there is in fact no need for it.

prefer this configuration, where only the single power supply equipment

All dual power supply equipment connects directly to a power rail

All dual power supply equipment connects directly to a power rail

it does require an extra power rail in the back of the rack.

There are some common techniques used in data centers

to increase availability of equipment

Quite obvious, try to deploy systems

with dual or triple power supply built in,

and connect these two dedicated utility feeds

and connect these two dedicated utility feeds

so the starting point is to determine

what the ICT system is used for

Arguably, in commercial data centers

this discussion may never take place,

having a customer who is responsible for their own ICT.

Nevertheless, as a commercial operator,

in advising the best possible solution

Carefully review the electrical diagram,

which ones are connected to the UPS,

and which ones are connected to the raw power supply of the building

If the computer room has a raised floor,

This will then automatically create some level of separation

These are switches, which are placed around a single point of failure

will allow you to bypass faulty equipment

or equipment which requires maintenance

Be aware that using wrap-around bypass switches at the UPS level,

does mean that no more power conditioning takes place once activated

in extraordinary circumstances when bypassing a UPS

Let's have a look at an example of a wrap-around bypass at the ATS level

the utility feed runs through the ATS,

and the power goes down stream towards the load;

During backup operations,

the ATS fails over to the generator, which will take over the load

So what happens in the scenario the ATS fails

or needs to undergo urgent maintenance?

In that scenario, the utility power bypasses the ATS.

the back up scenario will be that the generator feeds power to the load,

Some of these scenarios look frightening,

This since earlier I explained it is a break-before-make scenario,

and the switching time is not fast enough

you have your UPS systems installed,

Use breakers as much as possible

to create a proper isolation of various parts of the electrical system

and do not share breakers over multiple power rails or racks,

require the primary side of the aker to be wired to a common bus.

which means you would have to connect wires on a live powered bus

since often it is not allowed to work on an electrical board which is energised

It is however known that some contractors

are sometimes willing to do it anyway,

with the excuse that they did it before

and that they will be careful in doing so,

As part of proper data centre management,

you need to perform regular load checks,

and verify the presence of earth leakage

Keep imbalance to a minimum

and do not let it exceed 10-15%,

to avoid creating power quality issues

When you design the power infrastructure for the data center,

this since the data center environment is a very dynamic place

| this since the data center vironment is a very dynamic place

you have the choice of having the power infrastructure either overhead,

Where the raised floor is used for the purpose of cooling

installing the power cabling under the raised floor

should be done such that it has no or very minimal impact on the air flow

Another point to consider is the distance

and the network cabling is overhead, you have good separation

you need to keep proper separation between the copper network cabling

and power cabling to avoid electromagnetic fields issues on the network cabling

When installing both power and network cabling under the raised floor,

most designers will position the network cable at the back of the rack

or you can opt to use busbar trunking,

Traditionally, data centers apply power cabling inside the computer room

In this set-up, you have a power distribution board,

In this set-up, you have a power distribution board,

In this set-up, you have a power distribution board,

from which cables will run to the various locations within the computer room

but it does not give you any flexibility

but it does not give you any flexibility

If you have designed for the cabling to be single phase for each rack,

This often means a lengthy process of getting a few vendors to come to the site,

which will then happen in a production data center,

It is of course possible to use a mix of power ratings,

since you do not know what type of equipment you will deploy in the future

if you choose for overhead distribution

Alternatively, you may be able to take tiple single phases out of the busbar trunk.

which is determined by the type of tap-off boxes that you use

so this would give you a great flexibility in changing or adding capacity,

or to change from single to three-phase power to the rack, and of course vice versa

Busbar trunking is more expensive, so as a designer,

Busbar trunking is more expensive, so as a designer,

you need to balance the budget with flexibility

Do realise that they data center may operate 10-20 years,

and that during that time you will for sure get a lot of equipment chages

It is therefore a good idea to design for a flexible power infrastructure,

since it will easily outweigh the hassle

and additional costs that you may incur in the future

and additional costs that you may incur in the future

if you have to change the traditional power cabling infrastructure a number of times,

due to changes in the ICT equipment

This slide demonstrates the internal workings of the busbar trunk

As you can see. the busbar trunk is in fact a fully enclosed cable trunk

which are based on all five wires being the ground,

On top of the rail there are openings, which are normally covered,

and people cannot simply touch the actual power bars inside the trunk

which ultimately determine what type of power is coming out of the tap-off box,

In this configuration the breakers are at the tap-off points,

which means that during an overload or short circuit,

So. the breaker is now location-based instead of centralised.

which can be connected to the network to measure, either local or remote,

all electrical parameters at the tap-off point, and to monitor a power trip remotely,

Most busbar systems in the market have a fixed spacing between the tap-off points

This may result cable routing and management challenges,

when the tap-off point distance is not matching the rack spacing distance,

Some busbar systems have the ability for mounting the tap off point

or network cabling through a data center building

Trunking is commonly used to run the cables from the distribution board

Sometimes cable trunks are also used for network and high power cabling,

Sometimes cable trunks are also used for network and high power cabling,

in situations where cables need physical protection,

in situations where cables need physical protection,

because they may run through public areas

you should realise that the cabling is running through a full enclosure.

which will cause heat development within the trunk.

you derate the power rating down to 900 ampere maximum

In most cases, this is not a problem,

In most cases, this is not a problem.

since you will hardy ever operate at full power ratings in the data center,

Trays are used for both network and power cabin

such as in transformer rooms or generator rooms

such as in ransformer rooms or Generator rooms

such as in transformer rooms or generator rooms

Cable baskets are normally used for network cabling only

Cable baskets can be installed under the raised floor or hanging from the ceiling

These cable baskets are fairly lightweight and not extremely strong,

and therefore network cabling is commonly the only cable

The terms "grounding" and earthing" refer to the same principle.

as explained in the raised floor module

For the ICT equipment, you want the ground to be as noise-free as possible,

For the ICT equipment, you want the ground to be as noise-free as possible,

The best way to achieve this is by creating a dedicated ground for the computer room

causing noise on the ground, which therefore could end up in the data center

and similar applies to other ground systems

Since you are connecting to ground only at the low impedance ground pits,

you need to make sure that the ground resistance at the earth pit is low

you need to make sure that the ground resistance at the earth pit is low

The ground resistance can be measured by your electrical contractor,

As such, it is recommended to measure the ground resistance at least once a year

the raised floor, distribution boards,

fire alarm panels and any other metal objects that you can identify.

Common Mode Noise, shortly known as CMN

CMN is measured at the point where the ICT equipment is connected,

then the maximum allowed voltage between ground and neutral

Most of the ICT equipment manufacturers

it could pose a risk in a variety of ways

Secondly, if you violate the maximum level set by the manufacturer,

for power to the equipment

In the building, you normally have a bonding point between the ground and the neutral

directly after the building transformer

Since there is a direct bond, between ground and neutral,

at this point you will measure zero volt

there will be a potential long run of cables through the building,

When the current runs through a cable,

and as a result the voltage between neutral and ground will increase,

one option is to make sure that power loads are property balanced

Theoretically, you can argue that you could force another bonding pc

as it will create serious safety issues

However, what is allowed and what you can do in an electrical installation,

is simply putting another transformer

and then after that transformer again connect the ground to the neutral

what is called an isolation transformer

The principle of this type of transformer is indicated on this slide

at the primary side of the transformer,

you have four wires coming in, being three live wires and the ground

Syou have four wires coming inj ing three live wires and the ground

On the secondary side of the transformer,

being the output of the transformer

you have the ground wire, the three live wires and the brand new neutral wire

This neutral wire has nothing to do with the existing neutral wire in the building,

between this new independent neutral and the ground as its the first bonding point

Therefore, at this point the voltage between around and neutral is zero

Therefore, at this point the voltage between ground and neutral is zero

Therefore, at this point the voltage between ground and neutral is zero

Therefore, at this point the voltage between around and neutral is zero

Therefore, at this point the voltage between ground and neutral is zero

the input transformer looks like a delta ■star and the output looks like a wye

Therefore, the isolation transformer is often called a delta-wye transformer

and does not do any voltage conversion,

as for which you normally use transformers in electrical installations

which is feeding the computer room

The location of this centralised isolation transformer

could be in the UPS room or somewhere near the computer room

you run the power cabling to the various power distribution boards,

since the longer the distance between this bonding point and the rack,

the higher the voltage that could build up between the neutral and the ground

or IEEE as they are commonly known,

recommends the distance between this bonding point and the ICT equipment

Another option is to have an isolation transformer in every distribution board,

The principal is based on the fact that the distribution boards

The principal is based on the fact that the distribution boards

Therefore, having the isolation transformer inside the distribution board

will ensure that the ground to neutral bonding point

will be close to the ICT equipment, which the best possible location

Distribution boards with a transformer built-in are also larger in size,

potentially taking up too much space,

which could have been used for ICT equipment racks instead

Designers, therefore, need to review each individual case

and strike the best balance between optimum electrical performance

versus space and cost considerations

The connection is established through use of the magnetic flux principle

In addition to the reduction of common mode noise due to the new bonding point,

this galvanic isolation also achieves some limited noise filtering

this galvanic isolation achieves some limited noise filtering

An issue which you need to address in the data center environment,

Harmonics are basically power disturbances.

Therefore, you need to make sure that ■the transformer can handle the heat

generated by these harmonics, and mis is addressed with the K-Factor.

The higher the K-factor of a transformer

In data centers, the recommendation is o use K-13 type of isolation transformers,

especially when older legacy equipment is still in operation.

so some data centers are now opting for lower K-Factor transformers

It is advised to discuss with your electrical consultant,

to make sure you choose the right K-Factor rating for your data center environment

In computer rooms with high harmonic content,

you may want to consider upgrading the neutral wire to double the normal size.

and therefore less voltage creation

| if there are high neutral currents is a result of harmonics and imbalance

There are a number of international standards which apply to distribution boards

then make sure that the boards are tested and approved by the local authorities

You can imagine that if something would happen within the board, such as for example

and therefore potentially the most damaging component should it develop a fault.

and in this case, a breaker is a functional component

and in this case, a breaker is a functional component

Basically it means that each busbar and each breaker have its own compartment,

so even when the breaker would explode,

but now also the termination of each functional component has a compartment

This is the best option for mission-critical high power distribution boards,

Note that in some countries electrical code [dictates certain type of boards to be used,

depending on the current and voltage rating of an electrical board

And in addition to this, there is also separation between all functional components

but now also the termination of each functional component has a compartment

The right hand side shows an example of a cross section of such board

between the various functional components,

On the right hand side is a cross section lot a form factor four distribution board.

The power cables connect to the breaker, ■but enters into a small compartment

The power cables connect to the breaker, but enters into a smal compartment.

However it does come with a price and that needs to be justified

UPS systems, air conditioners, generators,

the first number indicates the level of protection against a physical objects,

the second number indicates the level of protection against liquids

If equipment is going to be installed outdoors, for example an outdoor generator set,

then it will be exposed to rainfall, and therefore a higher level of protection

then it wil be exposed to rainfell, and (therefore a higher level of protection

Anyone familiar with IP grades will however understand when yousaylP20/IP21

The table on this slide shows the level of protection presented by the first number,

the higher the number, the more protection is applied against physical objects

Level 0 offers no protection.

they require a higher level of protection

to placing equipment either indoors or outdoors

UPS systems are normally placed indoors,

This slide provides a visualization of how IP grades are practically being used,

you already get a very good indication of what level of protection is being offered

such as grounding and common mode noise.

IEC is short for International Electrotechnical Commission,

and specifically for the US the NEC being short for the National Electrical Code

Be aware that the specifications in these standards

Because of that, it is sometimes required

than what is described in these norms

A good example is the ground resistance,

As you may recall, the recommendation is

to have a ground resistance of less than 1 Ohm for the computer room,

The standards indicate that the nominal voltage should be maintained

For frequency the tolerance is much lower,

being a maximum of 1 percent up or down

Common mode noise is limited to 1 percent of the phase to neutral voltage

and refers to non-linear loading factors,

ICT equipment is such non-linear load

In a perfect world, there is no distortion since the load would be a linear load,

which means that the current drawn by the load will be in sync with the voltage,

However, due to the switched mode power supplies which are used in computer systems,

On this slide an example of linear loads,

Now we have a look at non-linear loads,

as a result of the switch mode power supply in the computer system,

So, the conclusion - harmonics are disturbances in the electrical system.

depending on the country you are operating your data center

UPS and air conditioner equipment.

the sine wave could be impacted such

With harmonics being a very complex topic

remember that harmonics in an electrical installation are undesirable,

since they cause more heat dissipation,

Measurements are commonly conducted by consultant organisations

could alsohave a negative impact on the generator

could also have a negative impact on the generator,

which may require the generator to be oversized

which may require the generator to be oversized

This is technically possible, but it can turnout to be very costly in doing so

To counter harmonics, consider the usaae of active or passive filters

How do harmonics relate to the UPS?

Depending on the technology used,

The rectifier is the input stage of UPS,

which is converting the incoming alternating current,

In simple terms, it takes the 50 or 60 hertz building power,

and converts it into battery voltage, which is used inside the UPS

and converts it into battery voltage, which is used inside the UPS

and converts it into battery voltage, which is used inside the UPS

Simply said, out of a full sine wave

less pulses means more energy needs to be absorbed during each pulse,

a 6 pulse rectifier can cause as much as 30 percent disturbance

IGBT is shorty for Insulated Gate Bipolar Transistor,

IGBT is short for Insulated Gate Bipolar Transistor,

which is similar to a Thyristor rectifier,

The IGBT rectifier will create1 less disturbance on the supply,

The IGBT rectifier wil create less disturbance on the supply.

The IGBT rectifier will create less disturbance on the supply,

Again, the resulting effect of the high harmonic levels is the Generation of heat

voltage should be within 10 percent tolerance of the nominal voltaqe,

and the sine wave of the voltage should not be disturbed too much,

therefore take note of the limits mentioned on this slide

This slide visualises the CBEMA curve.

mostly called ITIC curve these days

This curve indicates what voltage levels are acceptable for ICT equipment

All manufacturers will comply to the CBEMA curve.

which means that as long as you keep your voltage within this curve,

which means that as long as you keep your voltage within this curve,

equipment manufacturers will guarantee that the equipment operates as specified

The 100% indicator represents the nominal voltage as it is in a given country.

is the zone in which the voltage needs to be. which feeds the ICT equipment

If the supply voltage ends up in this zone, the ICT equipment may get damaged

The lower right hand zone Ted to as the "no damage region"

If the supply voltage ends up in this zone,

your system will most likely shutdown

You may remember the explanation for the static transfer switch (STS) earlier in this module

If there is a power interruption with a duration less than twenty milliseconds,

the equipment will continue to ooerate thanks to the CBEMA curve

the equipment will continue to operate thanks to the CBEMA curve

If you look at the horizontal part of the graph,

you can identify the twenty milliseconds,

and even if the voltage is zero percent, it is still in the green zone.

But if the voltage is zero percent land it exceeds the twenty milliseconds,

you end up in the "no damage region”,

which causes your system to shutdown

This is related to the standards, which indicates that voltage should be nominal

Looking at the vertical part of the graph,

the ICT equipment may not get affected,

as long as the time is short enough for the equipment to handle the surge.

If you have a need for understanding the power quality going into the computer room

you can make use of power quality meters

Often this is being outsourced to a third party company,

Often this is being outsourced to a third party company,

who are able to measure the power going into the computer room,

comparing it to the requirements of the CBEMA curve

So far we have discussed grounding,

and the CBEMA curve, and these are all factors to consider

Can you recal the preferred maximum Ohm's level in grounding,

or the maximum voltage when mention Common Mode Noise?

or the maximum voltage when mention Common Mode Noise?

Okay, study these values for two reasons