introduction to mv switchgear

Introduction to MV Introduction to MV EQUIPMENTSEQUIPMENTS

Prepared by Triyanto Limantoro

Introduction to MV equipments Introduction to MV equipments Basic Magnitude in MV switchgear :

� Voltage

� Current

� Frequency

� Short Circuit power

� Voltage, rated current and rated frequency:

� Single line diagram / Specification

Schneider Electric 2- Industrial Division Σ July 2009

� Single line diagram / Specification

� to define the dielectric withstand of the components such

as: CB, insulators, CTs,VTs,etc

� Short circuit power :

� to choose various parts of a switchgear: withstand

against temperature rises and electro dynamic force.

VOLTAGE

� Operating/Service Voltage U (kV):

� Voltage across the equipment terminals.

� example : 22kV, 3.3kV,…

� Rated Voltage Ur (kV) : (nominal Voltage)

� Max rms (root mean square) value of the voltage that


� Max rms (root mean square) value of the voltage that

equipment can withstand under normal operating conditions.

� Rated voltage (Ur) is always greater than the operating voltage.

� Rated voltage associated with an insulation level

� Examples : Rated voltage 7.2kV, 17.5kV, 12kV and 24kV

VOLTAGE

�Insulation level Ud (kV rms, 1 minute) and Up (kV peak)

Definition: the electric withstand of equipment to switching under operation

over voltages and lightning impulse.

� Ud: Over voltage due to of internal switchgear, which accompany all

changes in the circuit: opening/closing CB or Switch, breakdown or shorting

across an insulator, etc…


� Simulated in laboratory/factory by the power-frequency withstand voltage for 1 minute.

� Example : Ur : 24kV � Ud : 50kVrms/1 min.

� Up: over voltage of external switchgear or atmospheric originoccur when lightning falls on or near a transmission line.

� Simulated in laboratory by the lightning impulse withstand voltage.

� Examples : Ur : 24kV � Up : 125kVp

� IEC Standard Voltage

20 7.2 60


20 7.2 60

12

17.5

24

36

Ur UpUd

170

12550

70

95

7528

38

1.2/50us 50Hz

� Standard

Schneider MV equipment is conformity with list 2 of the series 1

table IEC 60 071 and 60 298.

Rated

Voltage

Rated power-

frequency

withstand

voltage

Normal

operating

voltage

kV rms 1minute kV rms kV rms

list 1 list 2

Rated lightning

impulse

withstand voltage

1.2/50us 50Hz

.

kV peak


� Insulation level apply to MV swgr at altitudes of less than 1000

meters, 20 deg.C, 11 g/m3 humidity and press of 1.013 mbar.

� Above this ,derating should be considered.

list 1 list 2

7.2 40 60 20 3.3 to 6.6

12 60 75 28 10 to 11

17.5 75 95 38 13.8 to 15

24 95 125 50 20 to 22

36 145 170 70 25.8 to 36

Derating of the switchgear related to the altitude


� Altitude 2500 m �� k is equal to 0.85

� Impulse withstand of the switchboard must be :125/0.85 = 147.05 kV

� Power frequency withstand 50 Hz must be 50/0.85 = 58.8 kV

2500

� Standard

Insulation level corresponds to a distance in air which

guarantees withstand without a test certificate.

Rated

Voltage

Rated power-

frequency

withstand

voltage

Distance live

to earth in air

.

Rated lightning

impulse

withstand voltage

1.2/50us 50Hz

.


� lower than this distance, we need simulation/test in the

laboratory to check lightning impulse withstand voltage. Or using

additional insulation material such as heatshring, screen,etc

kV rms 1 minute kV rms cm

7.2 20 9

12 28 12

17.5 38 16

24 50 22

36 70 32

95

125

170

.

kV peak

60

75

Current

The rms value of current that equipment can withstand

when current flow without exceeding the temperature riseallowed in standards.

Temperature rises authorized by the IEC according to the

type of contacts.


OPERATING CURRENT : I (Ampere)

� Calculate from the load power.

� Actual current passes through the equipment.

• generally customer provide its value

• calculate if we know the power of the load

Exercise:

� A switchboard with a 630kW motor feeder and a 1250kVA

ηηηη


x’mer feeder at 5.5kV, cos ϕ = 0.85 and motor efficiency ηηηη =

90%

� How many ampere the operating current of Transformer

and Motor?

� In motor = 86.44 A

� In Trafo = 131.22AThe answer

Short Circuit Current

� Short circuit power depends on :

� Network configuration

(exp: single source, parallel source, network, generators)

� Impedance of each equipments or devices.

(exp: lines, cables, transformers, motors)

� Power short circuit is maximum power that network or source can deliver


� Power short circuit is maximum power that network or source can deliver

to an installation during a fault,

� expressed in MVA or in kA rms at operating voltage.

Exp: Psc = 500MVA @ 20KV or Isc : 31.5kA rms

� Determination of the short-circuit power requires analysis of the power

flows feeding the short circuit in the worst possible case.

�What is short circuit level for 500MVA @ 20KV ?

14.43kAAnswer

Short Circuit Current

D

E


� Isc at main busbar D when bustie D4 close?

� Isc at the outgoing feeder E?

E

Minimum short-circuit current: Isc (kA rms.)

� Corresponds to a short circuit at one end of the fault point.

� This value allows us to choose the setting of thresholds for over

current protection devices(F50/F51) and fuses

�Example: Isc: 23 kA rms


source load

Ith Isc

Maximum short-circuit current: Ith (kA rms. 1 s or 3 s)

� Corresponds to a short circuit in upstream terminals of the

switching device,

� express in : kA for 1s or 3 s

� thermal withstand of the equipment = Ith

� Example: Ith: 31.5 kA rms. 1 s or 3 s


source load

IscIth

Peak Value of the max. short circuit current (kA peak)

� Value of the initial peak in the transient period

� I dynamic (kA peak) is equal to :

� 2.5 x Isc at 50 Hz (IEC)

� 2.6 x Isc at 60 Hz (IEC)

� 2.7 x Isc (ANSI) times the short circuit current calculated at a given

point in the network.


� Example: Isc : 25kA � Idyn: 2.5 x 25= 63.75kA peak (IEC 60 056)

� Idyn: 2.7 x 25= 67.50kA peak (ANSI), 25kA at

a given point

� This value determines the breaking capacity and making (closing) capacity of CBs and Switches, as well as the electro dynamic withstand of

busbars and switchgear.

� Isc value based on IEC: 8 – 12.5 – 16 – 20 – 25 – 31.5 – 40- 50 kA rms

Frequency fr (Hz)

� 2 different frequency use in the world:

50 Hz in Europe

60 Hz in the USA

several countries use both frequencies indiscriminately

� Instrument Voltage Transformer rated 50 can operate at 60Hz

� Instrument Current Transformer rated 50 can operate at 60Hz.


� Instrument Current Transformer rated 50 can operate at 60Hz.

But CT with rated 60Hz can not be operated at 50Hz.

Electrical network can be disconnect, protect and control by using AIS SWITCHGEAR :

AIR INSULATED SWITCHGEAR (AIS)

METAL enclosed switchgear divided 3 types:

� Metal clad : example: MC set,NEX

� Compartmented : example: SM6

� Block : example Interface/joggle cubicle.

Introduction to MV equipments Introduction to MV equipments


� Block : example Interface/joggle cubicle.

DIFFERENT ENCLOSURE TYPE (AIS)

metal clad

LSC2B


compartment

Block type

LSC2A

LSC1

GIS

MV Switchgear to IEC 62271-200 Fully enclosed in metal enclosure and having some current carrying capacity

Loss of Service Continuity

Class (LSC)

• Architecture based on “safe compartment access”

LSC 2A

• Safe access to compartment

• With power flow in busbar and the other units

• MV Cables must be earthed

• Safe access to compartment

LSC 2B

Maintainability of defined parts

Maintainability of one functional unit allowing normal service of the remaining units of the switchboard (busbar in a separate compartment)

Several levels of service continuity during maintenance


compartment

• With power flow in busbar and the other units

• MV Cable in separate compartment

• Cable of unit under maintenance can remain energized

• Metal enclosed not of LSC2 class

LSC 1

defined parts with no need of cable disconnection (separate cable compartment)

MOTORPACTMOTORPACT

MCSET or NEXMCSET or NEX

Partition Class PM

• All partitions and shutters of safe access compartment shall be metallic with some current carrying capacity

“Metal enclosed” compliant during maintenanceApplicable mainly to withdrawable system

Partition ClassI or M

• Classification based on electrical field presence in safe access compartment

Personnel comfort during maintenance

MV Switchgear to IEC 62271-200 Fully enclosed in metal enclosure and having some current carrying capacity

MCset or PIXMCset or PIX


Partition Class PI

• Partitions or shutters may be partially or totally of insulating material

Electrical and mechanical safety according to IEC 60466 or 60137

3.110 Shutter

Part of metal-enclosed switchgear and controlgear that can be moved from a position where it permits contacts of a removable part, or moving contact of a disconnector to engage fixed contacts, to a position where it becomes a part of the enclosure or partition shielding the fixed contacts.

MotorpactMotorpact

Definition

MV Switchgear to IEC 62271-200 Fully enclosed in metal enclosure and having current carrying capacity

IAC classified

• No projection of parts towards accessible sides

• No ignition of indicators

Safety in case of internal fault during service conditionDemonstrated by type tests(completely defined by the standard)

Internal Arc ClassIAC

• Classification based on consequences of internal arc on personnel safety

Personnel safety in case of internal arc

IAC not classifiedAccessibility TypesMotorpactcomplies with


IAC not classified

• No tests performed to assess behavior of enclosure under arc conditions

• A : restricted to authorized personnel only.

• B : unrestricted, including general public.

• Enclosure Identification code: F - for Front side

• L L - for Lateral sideR - for Rear side

Accessibility Typescomplies with AFLR type

SWITCHGEAR FUNCTION


STANDARDS DISTRIBUTION FEEDERS (AIS)

The MCset range meets the following international standards:

62271-1 : clauses common to high voltage switchgear

62271-200 : metal-enclosed switchgear for alternating current at

rated voltages of between 1 and 52 kV

IEC 62271-100 : high voltage alternating current circuit breakers

IEC 60470 : high voltage alternating current contactors

IEC 60265-1 : high voltage switches

IEC 60282-2 : high voltage fuses


IEC 60282-2 : high voltage fuses

IEC 60271-102 : alternating current disconnectors and earthing

switches

IEC 60255 : measurement relay and protection unit for the

applicable parts

IEC 60044-1 : current transformers

IEC 60044-2 : voltage transformers

IEC 60044-8 : electronic current transformers (for LPCT).

STANDARDS MOTOR STARTER / MCC (AIS)

Motorpact meets IEC standardsIEC 62271-1 High-voltage switchgear and controlgear – Part 1: CommonspecificationsIEC 62271-200 AC metal-enclosed switchgear and controlgear for ratedvoltages above 1 kV and up to and including 52 kVIEC 60470 High voltage alternating current contactors and contactorbased motorstartersIEC 60282-1 High voltage fuses: limiting fusesIEC 62271-102 Alternating current disconnectors and earthing switchesIEC 60044-1 Instrument transformers - Part 1: current transformersIEC 60044-2 Instrument transformers - Part 2: inductive voltage transformers


IEC 60044-2 Instrument transformers - Part 2: inductive voltage transformersIEC 60044-8 Instrument transformers - Part 8: electronic current transformersIEC 61958 High-voltage prefabricated switchgear and controlgearassemblies - Voltage Presence Indicating SystemsIEC 60076-11 dry-type transformers

Other specificationsIACS International Association of Classification Societies

STANDARDS DISTRIBUTION FEEDERS (GIS)


SF6 and Vacuum

�SF6 is used for insulation and breaking functions:

�That is the only used technique for all voltages, in

secondary distribution (switches, RMU) and in high voltage

up to 800 kV.


�Vacuum is limited to the breaking function and only in medium voltage (mainly up to 36 kV):

�The vacuum bottles have dielectric weakness

(NSDD - contact surface state).

SF6 and Vacuum are two modern breakingtechniques used in Medium Voltage.

�They ensure the continuity of service expected by the users together with complete safety.

�The SF6 technique has differentiating advantages :


for specific applications (capacitor banks,

motor breaking, generator , etc …),

for particular network operating modes (e.g. on line

monitoring of breaking medium).

Equivalent reliability of SF6 and Vacuum CB ’s

�Excellent reliability for both techniques:

�experience built up by manufacturers and users,

�upgrading and optimization of equipment through the use of

modern development methods (CAD-CAM, FMECA, …)

�mastering of « sensitive » components such as operating


�mastering of « sensitive » components such as operating

mechanism and tightness.

�The actual failure rate on the installed 180 000 circuit-breakers throughout the world is :

�4/10 000 per year ==> MTBF ~ 2800 years.

Minimum maintenance for SF6 and Vacuum installed circuit-breakers

�SF6 pole-units and vacuum enclosures:

�are sealed for life,

�are maintenance free,

�have mechanical and electrical endurance that is much

greater than actual needs (several tens of times Isc,

10,000 Ir).


10,000 Ir).

�Operating mechanism:

�is based on the same technology, whatever the technique,

and is a component with high mechanical endurance

(10,000 operations minimum).

�The lifetime of the SF6 Merlin Gerin circuit-breakers is 30 years.

Installation security: assets of SF6.

�On-line monitoring of the breaking medium ispossible thanks to a pressure switch .


�All the ratings at the pressure switch level.


�No overvoltage having detrimental effect on the equipment:

�No reignition nor restrike, during the switching of capacitors

banks.

�No or weak overvoltage during the switching of inductive

loads


loads

(unloaded transformer, starting motor).

�No NSDD ’s during breaking, nor multiple prestrikes in

making.

�The use of vacuum circuit-breakers requires to have overvoltage protection (ZnO-RC).

U source side

U load side


SF6 circuit-breaker (12kV)

U source side

U load side


45 kV

Vacuum circuit-breaker (12kV)


�Rated characteristics maintained at 0 bar gauge SF6 pressure with breaking once at 80 % or 100 % of the maximum breaking capacity and a dielectric withstand atleast 80 % of the insulation level, for example:


�SF1 circuit-breaker at 0 bar gauge: 25 kA at 24 kV

125 kV BIL.

Safety of people related to the switchboards which the circuit breakers are integrated.

�Preponderance of the toxicity of copper vapours present in all electrical equipment in the event of internal arcing, whatever breaking technique.

�The information is in the IEC report 1634:


�The information is in the IEC report 1634:

Use and handling of SF6 in high voltage switchgear and controlgear.

SF6 or vacuum which one is the best technology in circuit breakers to the user’s view point ?

• Both can be safe, long lasting, adapted to the utilisation.• It all depends upon who is the manufacturer.• You can be confident when he is Schneider (Merlin Gerin-MG) who

A COMPARISON OF SF6 AND VACUUM CIRCUIT BREAKERS


is the most experienced maker of MV switchgear with SF6 and an expert in vacuum.•But the technologies have different features and merits which are compared in the attached document.

DIELECTRIC WITHSTAND

depends on 3 parameters:

� The Dielectric strength of the medium

� The Shape of the parts

� The distance :

� ambient air between the live parts


� ambient air between the live parts

� insulating air interface between the live parts

Dielectric Strength of air depends on ambient conditions:

� Pollution � reducing the insulating performance by a

factor <10. Pollution may occur from external dust, lack of cleanliness,

breaking down of an internal surface, pollution & humidity causes

electrochemical conduction which will worsen discharge phenomena.

� Condensation � reducing the insulating performance by a

. factor 3

� Pressure � related to the altitude, derating performance.

� Humidity � % of humidity can cause a change in insulating


� Humidity � % of humidity can cause a change in insulating

performances. (liquid always leads to a droop in performance)

� Temperature � temp. increases can cause decreases insulation performance. Thermal shock can be the cause of the micro

fissuration which can lead very quickly to insulator breakdown. Insulator

expands by 5 and 15 times more than a conductor.

� The Shape of the parts

� It is essential to eliminate any “peak” effect to avoid disastrous effect on the impulse wave withstand in particular and on the surface ageing of insulator.

� Air Ionization � Generate Ozone � Breakdown of insulator surface or skin

� Distance between parts

(there is ambient air between live parts)

� For installations sometime we can not test under impulse conditions, the table below gives the minimum distance to comply with in air either phase to earth or phase to phase .

�The table based on IEC 71-2 according to the rated lightning impulse withstand voltage and these distances guarantee correct withstand for unfavorable configurations: altitude < 1 000 m.


configurations: altitude < 1 000 m.

Note : the table above does not include any increase which could be required to take account of design tolerances, short circuit effects, wind effects, operator safety, pollution, etc.

INSTRUMENT TRANSFORMER


Metering transformer applicationsInstrument transformers are necessary to provide values

that can be used by these devices which can be analogue

devices, digital processing units with a microprocessor,

after analogue/digital conversion of the input signal (e.g.:

Sepam or Power Logic System).

Current transformer


Current transformers (CT) meet standard IEC 60044-1.

InsulationCharacterized by the rated voltage:

� of the insulation, which is that of the installation (e.g.: 24 kV)

� of the power frequency withstand 1 min (e.g.: 50 kV)

� of the impulse withstand (e.g.: 125 kV).

� Rated frequency

Characteristics Of Current Transformer:Based on standard IEC 60044-1.


� Rated frequency50 or 60 Hz.

� Rated primary current (Ipn)Rms value of the maximum continuous primary current.

Usual values are 25, 50, 75, 100, 200, 400, 600 A.

Rated secondary current (Isn)This is equal to 1 A or 5 A.

� Rated transformation ratioKn = I rated primary / I rated secondary (e.g.: 100 A / 5 A)

� Short-time thermal current Ith - 1 second



� Short-time thermal current Ith - 1 secondThis characterizes the thermal withstand under short circuit conditions

for 1 second.

It is expressed in kA or in a multiple of the rated primary current (e.g.: 80

x Ipn) for 1 second.

The value for a duration that is different to 1 second is given by:

I’th =SQRT ( Ith^2 / t ) � Ith : 16kA/1 sec, I’th for 2 sec : SQRT (16^2/2) = 11.31kA/2sec


Short-time thermal current peak valueThis value is standardized from Ith - 1 s at:

� IEC: 2.5 Ith at 50 Hz and 2.6 Ith at 60 Hz

� ANSI: 2.7 Ith 60 Hz.

Accuracy load


Accuracy loadThe value of the load on which is based the metered current accuracy

conditions.

Accuracy power PnApparent power (VA) that the CT can supply on the secondary for the

rated secondary current for which the accuracy is guaranteed

(accuracy load).

Usual values 5 - 7.5 - 10 - 15 VA (IEC).

Accuracy classDefines the limits of error guaranteed on the transformation ratio and

on the phase

shift under the specified conditions of power and current. Classes 0.5 and 1 are used

for metering class P for protection.



Current error ε (%)Error that the transformer introduces in the measurement of a current when the transformation ratio is different from the rated value.

Phase shift or phase error ψ (minute)Difference in phase between the primary and secondary currents, in angle minutes

magnetization curve (for a given temperature and frequency).

This magnetization curve (voltage Vo, magnetizing current function Im) can be divided into 3 zones:1 - non-saturated zone: Im is low and the voltage Vo (and therefore Is) increases virtually proportionately to the primary current.2 - intermediary zone: there is no real break in the curve and it is difficult to situate a precise point corresponding to the saturation voltage.3 - saturated zone: the curve becomes virtually horizontal; the error in transformation ratio is high, the secondary current is distorted by saturation.


Metering CTThis requires good accuracy (linearity zone) in an area close to the normal service current; it must also protect metering devices from high currents by saturating earlier

Protection CT


Protection CTThis requires good accuracy at high currents and will have a higher precision limit (linearity zone) for protection relays to detect the protection thresholds that they are meant to be monitoring.

SafetyThe CT secondary is used at low impedance (virtually in short circuit).

The secondary circuit should never be left open, since this would

mean connecting across an infinite impedance. Under these conditions,

hazardous voltages for personnel and equipment may exist across the

terminals.

Terminal markingCT connection is made to the terminals identified according to the IEC:

� P1 and P2 on the MV side

� S1 and S2 on the corresponding secondary. In the case of a double

output, the first output is identified by 1S1 and 1S2, the second by 2S1


output, the first output is identified by 1S1 and 1S2, the second by 2S1

and 2S2.

CT for meteringAccuracy class� A metering CT is designed to send as accurate an image as possible of

currents below 120% of the rated primary.

� Accuracy guaranteed from load 25% and 100% of the accuracy power.

� IEC standard 60044-1 determines the maximum error:


CT for metering

Safety factor: FSIn order to protect the metering device connected to the CT from high currents on the MV side, instrument transformers must have early saturation characteristics.The limit primary current (Ipl) is defined for which the current error in the secondary is equal to 10%. The standard then defines the Safety Factor FS.:


This is the multiple of the rated primary current from which the error

becomes greater than 10% for a load equal to the accuracy power.

CT for protection� Accuracy class

A protection CT is designed to send as reliable an image as possible of the fault current (overload or short circuit).

� IEC standard 60044-1 determines the maximum error for each accuracy class in the

phase and in the module according to the indicated operating range.


For example for class 5P the maximum error is y ± 5% at the accuracy limit current

and y ± 1% at the rated current.

Standardized classes are 5P and 10P. The choice depends on the application.

The accuracy class is always followed by the accuracy limit factor.

Accuracy limit factor: FLPA protection CT must saturate at sufficiently high currents to enable sufficient

accuracy in the measurements of fault currents by the protection device whose

operating threshold can be very high.

The limit primary current (Ipl) for which current errors and phase shift


The limit primary current (Ipl) for which current errors and phase shift

errors in the secondary do not exceed values in the table below

The standard then defines the accuracy limit factor FLP.

In practice this corresponds to the linearity limit (saturation curve) of the CT.

� If ϕ and η are not known, use

approx value cos ϕ: 0.8 and η =

0.8

� Capacitor Feeder :Derating

coefficient of 30% to take into

account of temp. rise due to

capacitor harmonic


� Bus section

The greatest value of current that

can flow in the bus section on a

permanent basis.

Ips = In bus

� Standardized values :

10-12.5-15-20-25-30-40-50-60-75-80 and their multiples and factors

� CT must be able to withstand 120% the rated current

CURRENT TRANSFORMER

Example:

A thermal protection device for a motor has a setting range of between 0.6 and 1.2 x Ir (CT).

In order to protect this motor, the required setting must correspond to the motor’s rated current.

� If we assume that Ir for the motor = 45 A, the required setting is therefore: 45A

� If we use a 100/5A CT, the relay will never see 45A , because: 100A x 0.6 = 60A > 45A.

� If we use a 75/5A CT, the relay will see , 75 x 0.6 = 45 A

� The range of setting will be: 0.6 < 45/75 < 1.2 . This CT is suitable.

RATED THERMAL SHORT CIRCUIT CURRENT (Ith)


RATED THERMAL SHORT CIRCUIT CURRENT (Ith)

� Value of the installation max. short circuit current and the duration 1s or 3 s.

� Each CT must be able to withstand short circuit current both thermally and dynamically until the

fault is effectively cut off.

� Ith = Ssc / (U x V3), Ssc = power short circuit MVA

� When the CT is installed in a fuse protected, the Ith = apprx. 80 Ir.

RATED SECONDARY CURRENT:

� Local use or inside switchgear Isr = 5A

� Remote use or long distance Isr = 1A

INSIDE MV CURRENT TRANSFORMER


� RATED PRIMARY VOLTAGE (Upr)

� According to the design, VT will be connected :

� Phase to earth 22.000V/V3 / 110V/V3, where Upr = U/V3

� Phase to phase 22.000 / 110V, where Upr = U

� RATED SECONDARY VOLTAGE (Usr)

� Phase to phase VT, rated secondary voltage : 100V or 110 V

� Phase to Ground VT, rated secondary voltage : 100/V3 or 110V/V3


� RATED OUTPUT

� The apparent power output that VT can supply the secondary circuit when connected at rated primary voltage and connected to the nominal load.

� It must not introduce any error exceeding the values guaranteed by the accuracy class . (S = V3. U. I in 3 phase circuit)

� Standardized value are:

10-15-25-30-50-75-100-150-200-300-400-500 VA

ACCURACY CLASS

� The limits of errors guaranteed in terms of transformation ratio and phase under the specified conditions of both power and voltage.

PROTECTION ACCORDING TO IEC 60 186


PROTECTION ACCORDING TO IEC 60 186

� Classes 3P and 6P (but in practice only class 3P is used)

� The accuracy class is guaranteed for values :

� of voltage of between 5% of the primary voltage and the max. value of this voltage which is the product of the primary voltage and the rated voltage factor (kT x Upr)

� For secondary load between 25% and 100% of the rated output with a power factor of 0.8 inductive.

INSIDE MV VOLTAGE TRANSFORMER


� INDEX PROTECTION

� Protection of people against direct contact and protection of

equipment against certain external influences.

� Requested by international standard for electrical installations

and products (IEC 60 529)

INDEX PROTECTION OF THE SWGR


and products (IEC 60 529)

� The protection index is the level of protection provided by an

enclosure against access to hazardous parts, penetration of

solid foreign bodies and of water.

�The IP code is a coding system to indicate the protection

index.

INDEX PROTECTION- first index


INDEX PROTECTION: second index


INDEX PROTECTION : third index

Definitions

� The protection mentions correspond to impact energy levels expressed in joules

� hammer blow applied directly to the equipment

� impact transmitted by the supports, expressed in terms of vibrations therefore in terms of frequency and acceleration

� The protection indices against mechanical impact can be checked by different types of hammer: pendulum


be checked by different types of hammer: pendulum hammer, spring-loaded hammer or vertical free-fall hammer (diagram below).

PROTECTION INDEX: third index


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