MiniatureCircuit Breakers

Reliable solutions for protection of installations

against over-current phenomenon

Advantages for you :• Bi-connect terminals for simultaneous termination of bus bar

& wires

• Unique pull up terminals design with safety shutters for

enhanced safety of users

• Positive contact indicator

• Line-load reversibility

• Low watt losses, saves energy

• High electrical life

• Wide range of accessories eg U/V release, over-voltage release,

shunt release, Aux & trip alarm conatcts

Technical data :• Conforms to IEC 60898-1, IS/IEC 60898-1:2002

• Ratings – 0.5 to 63 A

• No. of poles – 1P, 2P, 3P & 4P

• Tripping characteristics – B, C & D curves

• Breaking capacity – 10kA (as per IS/IEC 60898-1:2002)

• Suitable for Isolation as per IEC 60947

• CE and RoHS compliant

Experttips

– high breaking capacity

– better protection of cables and

equipments

– low let through energy

– line load reversible

– more safety to the user

– positive contact indication

– indicates actual contact position

– overvoltage release MZ209

– undervoltage release

– shunt release

– auxiliary contact & trip alarm

contact for on-off & trip indication

User friendly terminal design

10kA breaking capacity with

energy limitation class 3

Positive contact indicator

Wide range of accessories

Red : ON

Green : OFF

– bi-connect terminal

– pull-up design

– safety shutter (IP2X)

Description

• Protects circuits against over-

load & short circuit faults

• Provides isolation to down-

stream circuits

Technical data

• Conforms to

IEC 60898-1:2002

IS/IEC 60898-1:2002

• Ratings - 0.5 to 63 A

• No. of poles - 1P, 2P, 3P & 4P

• Tripping curves - B, C & D

• Breaking capacity

10kA (as per IEC 60898-1)

15kA (as per IEC 60947)

• Suitable for isolation as per

IEC 60947

Features & benefits

• Positive contact indicator on

front face

• 10kA breaking capacity with

class 3 energy limitation

• Bi-connect terminals with

pull-up design

• Finger proof (IP2X) terminal

with safety shutters

• Line-load reversible

• RoHS compliant, “Green”

product

• Wide range of accessories are

available

Connection

25sq mm rigid cables

16sq mm flexible cables

Description Modules In (Amp) B Curve C Curve D Curve

1P 1 0.5 NC100N ND100N

1 1 NC101N ND101N

1 2 NC102N ND102N

1 3 NC103N ND103N

1 4 NC104N ND104N

1 6 NB106N NC106N ND106N

1 10 NB110N NC110N ND110N

1 16 NB116N NC116N ND116N

1 20 NB120N NC120N ND120N

1 25 NB125N NC125N ND125N

1 32 NB132N NC132N ND132N

1 40 NB140N NC140N ND140N

1 50 NB150N NC150N ND150N

1 63 NB163N NC163N ND163N

2P 2 0.5 NC200N ND200N

2 1 NC201N ND201N

2 2 NC202N ND202N

2 3 NC203N ND203N

2 4 NC204N ND204N

2 6 NB206N NC206N ND206N

2 10 NB210N NC210N ND210N

2 16 NB216N NC216N ND216N

2 20 NB220N NC220N ND220N

2 25 NB225N NC225N ND225N

2 32 NB232N NC232N ND232N

2 40 NB240N NC240N ND240N

2 50 NB250N NC250N ND250N

2 63 NB263N NC263N ND263N

3P 3 0.5 NC300N ND300N

3 1 NC301N ND301N

3 2 NC302N ND302N

3 3 NC303N ND303N

3 4 NC304N ND304N

3 6 NB306N NC306N ND306N

3 10 NB310N NC310N ND310N

3 16 NB316N NC316N ND316N

3 20 NB320N NC320N ND320N

3 25 NB325N NC325N ND325N

3 32 NB332N NC332N ND332N

3 40 NB340N NC340N ND340N

3 50 NB350N NC350N ND350N

3 63 NB363N NC363N ND363N

4P 4 0.5 NC400N ND400N

4 1 NC401N ND401N

4 2 NC402N ND402N

4 3 NC403N ND403N

4 4 NC404N ND404N

4 6 NB406N NC406N ND406N

4 10 NB410N NC410N ND410N

4 16 NB416N NC416N ND416N

4 20 NB420N NC420N ND420N

4 25 NB425N NC425N ND425N

4 32 NB432N NC432N ND432N

4 40 NB440N NC440N ND440N

4 50 NB450N NC450N ND450N

4 63 NB463N NC463N ND463N

NC110N

NC220N

NC316N

NC432N

Miniature circuit breakers 10kAtype NB, NC, ND

40

Description In (Amp) Modules Catalogue No.

HLF199S

HLF299S

HLF399S

1P 80 1.5 HLF180S

100 1.5 HLF190S

125 1.5 HLF199S

3P 80 4.5 HLF380S

100 4.5 HLF390S

125 4.5 HLF399S

2P 80 3 HLF280S

100 3 HLF290S

125 3 HLF299S

4P 80 6 HLF480S

100 6 HLF490S

125 6 HLF499S

HLF499S

Miniature circuit breakers 80-125A, 10kAtype HLF

41

Description

• Protects circuits against over-

load & short circuit faults

• Provides isolation to down-

stream circuits

Technical data

• Conforms to

IEC 60898-1

IEC 60947

• Ratings – 80A,100A &125A

• No. of poles - 1P, 2P, 3P & 4P

• Tripping curve - C

• Breaking capacity - 10kA (as

per IEC 60898 & 60947)

• Suitable for isolation as per

IEC 60947

Features & benefits:

• MCBs handle can be locked

in "off" position

• Large terminal capacity- upto

70 sq mm

• Steel reinforcement plate to

improve terminal strength

• Serrations on jaws to provide

better grip on cables

• Line-load reversible

• RoHS compliant, “Green”

product

• Wide range of accessories are

available

Connection capacity

• 35 sq mm flexible wire

(50 sq mm possible with

some cable end-caps)

• 70 sq mm rigid wire

IP2X terminals

(R1+R2) - where R1 is the resistance of the phase conductor within

the installation and R2 is the resistance of the circuit protective

conductor. These two components constitute the loop impedance

within the installation.

Therefore : Zs = Ze+(R1+R2)

Once the value of Zs has been established a suitable overcurrent

protective device has to be selected to ensure disconnection of an

earth fault within the specified time. The times are :

• 5 seconds for fixed equipment

• For portable equipment and for fixed equipment installed outside

the equipotential bonding zone, the disconnection times are

dependent on the nominal voltage to earth, i.e. 220 to 277 volts

= 0.4 seconds.

Zs by calculation

To establish whether the relevant disconnection time can be achieved

a simple calculation must be made, based on Ohm's law :

Uo (open circuit voltage)*lf(fault current) =

Zs (earth fault loop)

*voltage between phase and earth (240V)

The fault current (lf) must be high enough to cause the circuit

protective device to trip in the specified time. This can be established

by consulting the time/current characteristic for the protective device.

If the maximum trip time for the fault current calculated is less than or

equal to the relevant value (5s) for fixed equipment; 0.4s for portable

equipment) then compliance is achieved.

Zs by tables

The above procedure can be used for any type of protective device

providing a time/current characteristic curve is available. Frequently,

however, a much simpler method is available using tables listing

maximum Zs values which have been interpreted from the

characteristic curves for the relevant devices. Providing the system Zsis equal to or less than the value given in the table, compliance is

achieved.

Zs too high

I f the system Zs value is too high to achieve rapid enough

disconnection with the Overcurrent protective devices available then

it is necessary to use one of the two following methods:

• fit a cable with a large cross-section and consequently a lower

impedance. This may be a very expensive solution especially

when the installation is completed before the problem is

discovered.

• use a Hager residual current device (RCD). Subject to certain

conditions being met this provides a simple and economical

solution.

Example

Fig. shows a fixed circuit with an earth loop impedance Zs of

0.7 ohms protected with an NC 132 . The fault current (lf) will therefore

be Uo/Zs = 240/0.7 = 343A

By referring to the characteristic for NC 132 it can be seen that the

breaker will disconnect in 0.02 seconds for this current. The breaker

therefore easily satisfies the requirement for disconnection in

5 seconds.

If the circuit Zs was 2.0 ohms that the fault current would be :

240/2 - 120A and the disconnection time would be 10 seconds, in

which case compliance would not be achieved.

Fig. 3

Protection against overcurrent

Overcurrent - "A current exceeding the rate value. For conductors the

rated value is the current-carrying capacity".

Overload current - "An overcurrent occurring in a circuit which is

electrically sound".

Short-circuit current - "An overcurrent resulting from a fault of

negligible impedance between live conductors having a difference in

potential under normal operating conditions."

Protection against overload current

For the protection against overload current, protective devices must

be provided in the circuit to break any overload current flowing in the

circuit conductors before it can cause a temperature rise which would

be detrimental to insulation, joints, terminations or the surrounding of

the conductors.

In order to achieve this protection the normal current of the protective

device ln should not be less than the design current of the circuit lband that ln should not exceed the current-carrying capacity of the

conductors lz, and that the current causing effective operation of the

protective device l2 does not exceed 1.45 times the current-carrying

capacity of the conductor lz, expressed as

lb< ln< lz

l2<1.45lz

Protection against short-circuit current

Protective devices must be provided to break any short-circuit

current before it can cause danger due to thermal and mechanical

(elector-dynamic) effects produced in the conductors and

connections. The breaking capacity of the protective device shall not

be less than the prospective short-circuit current at the point at which

the device is installed. However lower breaking capacity is permitted

provided that a properly co-ordinated back-up device having the

necessary breaking capacity is installed on the supply side.

Positioning of overcurrent devices

Devices for the protection against overload and short-circuit must be

placed at the point where a reduction occurs in the current-carrying

capacity of the conductors. This reduction could be caused by a

change in the environmental conditions as well as the more obvious

change in the cross-sectional area of the cable.

There are of course exceptions to the general rule which relate to a

very few special applications.

An earth fault current of 343A causes a trip of

the magnetic protection in 20mS.

An earth fault current of 120A causes a trip of

the thermal protection in 10 seconds.

Circuit protection principle

108

The TT- Scheme :

The transformer neutral is earthed. The frames of the electric load are

also connected to an earth connection.

The IT-Scheme :

The transformer neutral is not earthed theoretically. In practice, it is

earthed via high impedance = 1500 Ohms.

The frames of the electrical loads are connected to the earth.

Standardised Earthing Schemes

In all countries, LV networks and load are earthed for safety reasons

to guarantee protection against electric current for persons.

Additionally, the Earthing System affects the choice of protection

devices employed in some cases.

The earthing schemes characterise the method of earthing the LV

neutral point of the HV/LV transformer (or of any source) and the

means of earthing exposed conductive parts of the related LV

installation.

The three earthing system internationally standardised and currently

adopted in many national standards are :

The TN system :

The transformer neutral is earthed. The frames of the electrical loads

are connected to the neutral. Several versions of TN schemes are :

TN-C scheme :

The neutral conductor is also used as a protective conductor and is

referred to as a PEN (Protective Earth and Neutral) conductor. This

scheme is not permitted for PEN conductor of less than 10mm2 and

for the portable equipment.

TN-S scheme :

The protective conductor and the neutral conductor are separate.

The use of PE and N conductors is mandatory for circuits of cross

section less than 10mm2.

TN-CS scheme :

In some installation the TN-C and TN-S schemes can be used

together. Such scheme are known as TN-CS. However, it is not

allowed to use the TN-C downstream of TN-S.

TN-S scheme

TN-C scheme

First Fault

Second Fault

Circuit protection principle

109

Power loss

The power loss of MCB's is closely controlled by the standards and

is calculated on the basis of the voltage drop across the main

terminals measured at rated current. The power loss of Hager circuit

breakers is very much lower than that required by the Standard, so in

consequences run cooler and are less affected when mounted

together.

The table below gives the watts loss per pole at rated current

For use with DC

Because of their quick make and break design and excellent arc

quenching capabilities Hager circuit breakers are suitable for DC

applications.

The following parameters must be considered.

1. system voltage:

Determined by the number of poles connected in series

2. short-circuit current:

3. tripping characteristics:

- the thermal trip remains unchanged

- the magnetic trip will become less sensitive requiring

derating by √2 the ac value.

No. of poles 1 pole 2 poles in series

Range Max Breaking capacity Max Breaking capacity

voltage L/R=15ms voltage L/R=15ms

NB, NC, ND 60V 10kA 125V 10kA

HLF 60V 15kA 125V 15kA

Characteristic curve B C D

Magnetic trip 50Hz dc 50Hz dc 50Hz dc

Irm1 3 In 4.5 In 5 In 7.5 In 10 In 15 In

Irm2 5 In 7.5 In 10 In 15 In 20 In 30 In

MCB rated 0.5 1 2 3 4 6 10 16 20 25 32 40 50 63 80 100 125current (A)

Watts loss 1.3 1.5 1.7 2.1 2.4 2.7 1.8 2.6 2.8 3.3 3.9 4.3 4.8 5.2 5 5.5 8per pole (W)

Characterist ics ML NB NC ND HLF

Poles SP+N SP DP TP FP SP DP TP FP SP DP TP FP SP DP TP FP

Rated operational 230 230/415 230/415 230/415 230/415

voltage Ue(V)

Nominal Current 6-40A 6-63A 0.5-63A 0.5-63A 80-100-125A

Breaking capacity 6kA 10kA 10kA 10kA 10kA

to IEC 60 898

Breaking capacity - 15kA 15kA 15kA 10kA

to IEC 60 947-2

Rated insulation 500V 500V 500V 500V 500V

voltage Ui(V)

Rated impulse 4000V 4000V 4000V 6000V 6000V

voltage Uimp (kV)

Electrical endurance

0.5 to 32A 10000 20000 20000 20000

40 to 63A 10000 10000 10000

80 to 125A 4000

NB, NC, ND

Characteristic curve C

Magnetic trip 50Hz dc

Irm1 5 In 7.1 In

Irm2 10 In 14.1 In

HLF (IEC 60-898)

Miniature circuit breakers

110

Latest national & international standards covering Low Voltage Circuit

Breakers provide the user with a better assurance of quality and

performance by taking into account the actual operating conditions of

the breaker. New definitions and symbols have been introduced

which should be committed to memory. Some of those most

frequently used are:

Ue : rated service voltage

Ui : rated insulation voltage (>Uemax)

Uimp : rated impulse withstand

lcm : rated short circuit making capacity

lcn : rated short circuit capacity

lcs : rated service short circuit breaking capacity

lcu : rated ultimate short circuit breaking capacity

l∆n : rated residual operating current (often called residual

sensitivity)

ln : rated current = maximum value of current used for the

temperature rise test.

∆t : trip delay of residual current devices

In addition, IEC 60898 sets out to provide a greater degree of safety

to the uninstructed users of circuit breakers. It is interesting to note

that the description "miniature circuit breaker" or MCB is not used at

all in the standard, but no doubt both manufacturers and users will

continue to call circuit breakers complying with IEC 60898 miniature

circuit breakers or MCBs for some time to come.

The scope of this standard is limited to ac air break circuit breakers

for operation at 50Hz or 60Hz, having a rated current not exceeding

125A and a rated short-circuit capacity not exceeding 25kA.

A rated service short-circuit breaking capacity lcs is also included

which is equal to the rated short-circuit capacity lcn for short-circuit

capacity values up to and including 6kA, and 50% of lcn above 6kA

with a minimum value of 7.5kA. as the circuit-breakers covered by

this standard are intended for household and similar use, lcs is of

academic interest only. The rated short-circuit capacity of a MCB (lcn)

is the alternating component of the prospective current expressed by

its r.m.s. value, which the MCB is designed to make, carry, for its

opening time and to break under specified conditions. lcn is shown on

the MCB label in a rectangular box with the suffix 'A' and is the value

which is used for application purposes. lcn (of the MCB) should be

equal to or greater than the prospective short-circuit current at the

point of application.

You will see from the curves that the inverse time delay characteristic

which provides overload protection is the same on all three. This is

because the standards required the breaker to carry 1.13 times the

rated current without tripping for at least one hour and when the test

current is increased to 1.45 times the rated current, it must trip within

one hour, and again from cold if the last current is increased to 2.55

times the rated current the breaker must trip between 1 and 120

seconds. The inverse time delay characteristic of all MCBs claiming

compliance with IEC 60898 must operate within these limits.

The difference between the three types of characteristic curves

designated 'B', 'C' and 'D' concerns only the magnetic instantaneous

trip which provides short-circuit protection.

* For type 'B' the breaker must trip between the limits of 3 to 5

times rated current

* For type 'C' the breaker must trip between the limits of 5 to 10

times rated current, and

* For type 'D' the breaker must trip between the limits of 10 to 20

times rated current

Often manufacturers publish their MCB tripping characteristics

showing the limits set by the standard and guarantee that any

breakers that you purchase will operate within these limits. So great

care should be taken when working with characteristics curves

showing lower and higher limits - on no account should you take a

mean point for application design purposes.

For cable protection applications you should take the maximum

tripping time and some manufacturers publish single l ine

characteristics curves which show the maximum tripping time. If the

design problem is nuisance tripping then the minimum tripping time

should be used and for desk top co-ordination studies, both lower

and upper limits have to be taken into account.

Energy limiting

Energy is measured in Joules. *James Prescott Joule proved that

thermal energy was produced when an electric current flowed

through a resistance for a certain time, giving us the formula :-

Joules = l2 x R x t or because we know that watts = l2R

Joules = watts x seconds

Therefore we can say that :

One Joule = one watt second

or energy = watts x seconds = l2R t

If the resistance (R) remains constant or is very small compared with

the current (I) as in the case of short-circuit current, then energy

becomes proportional to l2t. Which is why the energy let-through of a

protective device is expressed in ampere squared seconds and

referred to as l2t.

l2t (Joule Integral) is the integral of the square of the current over a

given time interval (t0, t1)

The l2t characteristic of a circuit breaker is shown as a curve giving

the maximum values of the prospective current as a function of time.

Manufacturers are required by the Standard to produce the l2t

characteristic of their circuit breakers.

The energy limiting characteristics of modern MCBs greatly reduce

the damage that might otherwise be caused by short-circuits. They

protect the cable insulation and reduce the risk of fire and other

damage. Knowledge of the energy limiting characteristic of a circuit

breaker also helps the circuit designer calculate discrimination with

other protective devices in the same circuit.

Because of the importance energy limiting characteristic the

Standards for circuit breakers for household and similar installations

suggests three energy limiting classes based on the permissible l2t

(let-through) values for circuit breakers up to 32A; class 3 having the

highest energy limiting performance.

All Hager MCBs are well within the limits of energy let-through set by

IEC 60898 for energy limiting class 3.

The circuit breaker can have the line\load connected to either top or

bottom terminals.

Miniature circuit breakers

111