103333596 Discrimination Setting

8/12/2019 103333596 Discrimination Setting

1/58

0.1kA 1kA 10kA

1E-2s

0.1s

1s

10s

100s

1E3s

1E4s

Curva Tempo-Corrente FFF

Discrimination of

protection devices

on installations

Janet Roadway

Product Manager, Power

Breakers


2/58

Topics of Discussion

Explaining the terminology

Degrees of discrimination

Different techniques to achieve discrimination

Backup protection

Protection devices

Any Questions?


3/58


4/58

Protection - Overload

What do we mean by a fault?

Overload

Operating condition in an electrically undamaged circuit which

causes an current to flow in excess of the full load current

Example: Starting condition during DOL start

If this type of fault continues indefinitely because of an anomolous

operating condition., damage begins to occur creating.


5/58

ProtectionShort Circuit

What do we mean by a fault?

Short Circuit

Operating condition in an electrically damaged circuit where there is an

accidental or intentional connection by a relatively low resistance

between two points of a circuit which are normally at different

voltages

This type of fault can generate high current flows, arcing and fire if

not cleared quickly


6/58

Discrimination

Coordinate devices to:

Guarantee safety for people and installations

Identify and exclude only the zone affected by a problem

Limiting the effects of a malfunction

Reducing the stress on components in the affected zone

Ensuring service continuity with good quality supply voltage

Achieving a valid compromise between reliability, simplicity and cost

effectiveness


7/58


Discrimination or Selectivity

To make it possible to isolate a part of an installation involved in a fault

condition from the overall system such that only the device located

immediately on the supply side of the fault intervenes


8/58

Discrimination

Needs

Fast Fault Detection

Fast Fault Elimination

Let-Through Energy Reduction

High Fault Current Withstanding

GO!WAIT!

FAULTCONTINUITY OF

SERVICEFAULT DAMAGE


9/58

A

B CFault oc curs h ere

X

X X



10/58


Total Discrimination

This means that the isolation described occurs for all fault

levels possible at each point of the circuit


11/58

AB

Prospect ive FaultCurrent Icc

I

t



12/58


Partial Discrimination

This means that above certain current levels there is

simultaneous operation of more than one protection device


13/58

AB

Prospect ive FaultCurrent Icc

I

t



14/58

Discrimination

Traditional solutions

Current discrimination

Time discrimination

Energy discrimination

Zone (logical) discrimination


15/58

Discrimination


Discrimination among devices

with different trip threshold

setting in order to avoid

overlapping areas.

Setting different device tripthresholds for different

hierarchical levels.


16/58

Discrimination


An example:


17/58


18/58

Discrimination

Time discrimination

Discrimination among devices

with different trip time settings

in order to avoid overlapping

areas

Setting different device tripdelays for different hierarchical

levels


19/58

Discrimination

Time discrimination

An example:

Electronic release L (Long delay) S (Short delay) I (IST)

E4S 4000 PR111-LSI R4000

E3N 2500 PR111-LSI R2500

S7H 1600 PR211-LSI R1600

Setting: 0.9

Curve: B

Setting: 1

Curve: A

Setting: 1

Curve: A

Setting: 8

Curve: D

Setting: 10

Curve: C

Off

Off

Setting: 10


20/58

Discrimination

Time discrimination

Applications: low complexity plant

Fault area: short circuit and overload

Discrimination limit current: low, depending

on the Icw of the upstream device

Discrimination levels: low, depending on the network

Devices: ACBs, MCCBs and devices with adjustable

time curves

Feasibility & discrimination study: easy

Customer cost: medium


21/58

Types of Discrimination

Energy Discrimination

Many Low Voltage protection devices such as Circuit breakers

and Fuses have the ability to limit the peak of the current let

through them to a value lower than the prospective short circuit

peak.

Any protective device which clears short circuits in less than 1/2

cycle of the sinusoidal wave (i.e 10mS for 50Hz) will current limit

to a certain degree

Energy based discrimination is the only way to determine true

discrimination between current-limiting devices


22/58

Discrimination


Discrimination among devices with different mechanical and

electrical behaviour depending on energy level

It is necessary to verify that the let-through energy of the circuit-

breaker upstream is lower than the energy value needed to complete

the opening of the CB downstream


23/58

Discrimination


An example:Time-currents Curve

Energy

discrimination

up to 24 kA


24/58

Discrimination


Applications: medium complexity networks

Fault area: Short circuit only

Discrimination limit current: medium/high

Discrimination levels: medium, CBs size

dependent

Devices: ACBs, MCCBs, MCBs & Fuses

Feasibility & discrimination study: medium complexity Customer cost: medium


25/58

Discrimination

Zone discrimination

Discrimination among devices in order to isolate the faultzone keeping unchanged feeding conditions of maximum

number of devices

Zone discrimination is implemented by means of an

electrical interlock between devices

Zone

1

Zone

2

Zone

3


26/58

Discrimination

Zone discrimination

Applications: high complexity plant

Fault area: short circuit, overload, ground fault

Discrimination limit current: medium,

depending on Icw

Discrimination levels: high

Devices: ACBs, MCCBs with dialogue and control

features Feasibility & discrimination study: complex

Customer cost: high


27/58


Cascading or Backup protection

Uses supply circuit breakers or fuses with currentlimitation effects to protect downstream devices fromdamage

The amount of energy let through (i2t) by the supply

device needs to be lower than that which can bewithstood without damage by the device on the load side

By using this effect it is possible to install devicesdownstream that have short circuit breaking capacities

lower than the prospective short circuit current


28/58

Back-up protection/Cascading

Back-up protection or Cascading is recognised and

permitted by the 16th Edition of the IEE WiringRegulations 434-03-01 and is covered by IEC 364-4-437

standard


29/58

Why Use Back-up Protection?

Substantial savings can be made on downstream

switchgear and enclosures by using lower short circuitratings

Substantial reductions in switchgear volumes can also

result


30/58

What about Discrimination?

Backup protection should not be confused with

discrimination.

Backup protection does not infer discrimination can be

achieved but in practice, discrimination is normally

achieved up to the maximum breaking capacity of the

downstream device

GO!WAIT!

FAULTCONTINUITY OFSERVICE FAULT DAMAGE

BACKUPDiscrimination


31/58

Practical Example

Problem:

Installation requires the use of Busbar rather than cable

to distribute electrical power.

Fault level calculations reveal 25kA prospective fault

level at the point of installation of standard MCB

distribution board


32/58

Practical Example

Solution - Using a standard Isolator as the distribution board

incoming device - all the MCBs would need to be

25kA or above

Using an MCCB as the incoming device such as anABB Tmax T3N250TMD100, 6kA S200 MCBs could

be safely used


33/58

A word of caution ...

Back-up protection can only be checked by laboratory

tests and so only device combinations specified by themanufacturer can be guaranteed to provide co-

ordination of this type.


34/58

Types of protection available

Fuses

Miniature Circuit Breakers

Moulded Case Circuit breakers

Air Circuit breakers


35/58

Typical fuse

Current (A)

Time (s)

Ultra Reliable

Standard CharacteristicHigh current limitation

effects

High threshold on low

overloads ( clears overloads

at approx 1.45x rated FLC)


36/58

Fuseless technology

Two main types:-

Thermomagnetic protection-

MCB and lower rated MCCB

plus older type protection

relays

Electronic protection

Microprocessor based relays

fed from CTs either external to

switches or integral within a

circuit breaker


37/58

Thermomagnetic

Thermal

curve

Time (s)

Current (A)

Magnet ic c urve

Offer thermal longtime

overcurrent protection using Bi-

metal technology ( operates at1.3x FLC)

Uses the magnetic effect of

short circuit currents to offer

shorttime short circuit

protection


38/58

Electronic Relays

Time (s)

Current (A)

Overcurrent functions such as:-

Long time overcurrent

Short time instantaneous

protection

Short time time delayed

protection

Ground fault or Earth fault

protection


39/58


40/58

Protection releases: general features

Complete set of advanced protection functionsRc D U

OT UV OV

RV

RP

MORE

Complete set of standard protection functions

MORE

Complete set of measurements functions

MORE

A V Hz

W VA VAR E THD


41/58

Data logger:a professional built-in fault recorder.

BACK

Data logg er: a profess ional bui l t- in faul t recorder.

Standard in PR122 and PR123

Recording of 8 measurements (currents and voltages);

Configurable trigger (i.e. During a fault);

Sampling frequency up to 4.800kHz;

Sampling time up to 27s;Output data through SD-Pocket or TestBus2.

Exclus ive from ABB SACE.

-500

-400

-300

-200

-100

0

100

200

300

400

500

time

Voltage L1-L2

Neutral

Current phase 1

Current phase 2

Current phase 3

C l i


42/58

So what is the secret to achieving a successful

discrimination study

The secret is to be aware of the capability of thetechnology you are using and to design your installation

within the limits of the protection you have chosen

Conclusion


43/58


44/58

Double S*

Used to obtain discrimination in critical conditions

Double G*

Two different protection curves, one with the signal coming from

internal CTs and the other from an external toroid

Dual Setting*

Two different set of protection parameters in order to protect in the best

way, two different network configurations (e.g. normal supply and

emergency supply)

Protectionreleases: news on standard protection functions

* = These features are available on PR123/P

BACK

MORE

MORE

MORE


45/58


46/58

Protection releases: news on standard protection functions

Without double S


47/58


With double S

BACK


48/58

Double G

Its possible to protect the network, with the same protection

release, against earth fault both upstream and downstream the

circuit-breaker

Restricted Earth Fault: the fault is upstream the LV circuit-

breaker


Restricted Earth Fault

MV LV


49/58

Double G

Its possible to protect the network, with the same protection

release, against earth fault both upstream and downstream the

circuit-breaker

Restricted Earth Fault: the fault is upstream the LV circuit-

breaker Unrestricted Earth Fault: the fault is downstream the LV circuit-

breaker


Unrestricted Earth Fault

MV LV


50/58

Double G

The combination of both Unrestricted and Restricted Earth Fault

protection is named Source Ground Return. The new PR123/P

is able to detect and to discriminate both earth faults

If the fault is downstream the LV circuit-breaker the PR123/P will

trip Emax circuit-breaker


L1

L2

L3

NPE

Trafo secondary windings

External toroid

Emax internal CTs


51/58

Double G

The combination of both Unrestricted and Restricted Earth Fault

protection is named Source Ground Return. The new PR123/P

is able to detect and to discriminate both earth faults

If the fault is downstream the LV circuit-breaker the PR123/P will

trip Emax circuit-breaker

If the fault is upstream the LV circuit-breaker the PR123/P will trip

the MV circuit-breaker


L1

L2

L3

NPE

Trafo secondary

windings

External

toroid

Emax internal CTs

BACK


52/58

Dual setting

It allows to program twodifferent protection parametersets in order to adapt them tothe different networkconfigurations

The most representative

example is a network withsupply by the utility and byemergency generator

With dual setting thediscrimination between CBs isguaranteed in both network

conditions



53/58

Dual setting

Normal network condition

CB A >>> closed

CB B >>> open

Discrimination is guaranteed

between A and C



54/58

Dual setting

Emergency networkcondition

CB A >>> open

CB B >>> closed

Discrimination is not

guaranteed between B and

C, due to the low settings

(protection of the generator)

of C protection functions



55/58

P t ti l d d t ti f ti


56/58

Protectionreleases: advanced protection functions

BACK

Residual current

Protection against directional short-circuit with adjustable time-delay

Protection against phase unbalance

Protection against overtemperature (check)

Protection against undervoltage

Protection against overvoltage

Protection against residual voltage

Protection against reverse active power

Thermal memory for functions L and S

Underfrequency

Overfrequency

D

U

OT

UV

OV

RV

RP

M

UF

OF

RC

P t ti l t f ti


57/58

Protectionreleases: measurements functions

BACK

Voltage (phase-phase, phase-neutral, residual). Accuracy: 1%

Power (active, reactive, apparent) Accuracy: 2,5%

Power factor Accuracy: 2,5%

Frequency and peak factor Accuracy: 0,1Hz

Energy (active, reactive, apparent, meter) Accuracy: 2,5%

Harmonics calculation (display of waveforms and RMS spectrum up to 40 th@50Hz)

Current (phases, neutral, earth fault). Accuracy: 1,5%

Protection releases: t f ti


58/58

Protectionreleases: measurements functions

BACK

Voltage (phase-phase, phase-neutral, residual). Accuracy: 1%

Power (active, reactive, apparent) Accuracy: 2,5%

Power factor Accuracy: 2,5%

Frequency and peak factor Accuracy: 0,1Hz

Energy (active, reactive, apparent, meter) Accuracy: 2,5%

Harmonics calculation (display of waveforms and RMS spectrum up to 40 th@50Hz)

Current (phases, neutral, earth fault). Accuracy: 1,5%

103333596 Discrimination Setting

Documents