HARSH M.C.B. adopting a better technology
in design, manufacturing and materials offer an ideal protection
to your electrical distribution stytem. Whatever be your application.
HARSH offer a better M.C.B. for overloads and short circuit protection.
HARSH Miniature Circuit Breakers are
available in two characteristic "B" series and "C"
series.
"B" series is available from
6 to 40 AMP (SP, DP, TP, TPN, FP) as par 240/415V, 50 Hz,
10KA confirms to IS:8828/1996, IEC: 898
"C" series is available from
6 to 63AMP (SP, DP, TP, TPN, FP) as par 240/415V, 50 Hz,
10KA confirms to IS:8828/1996, IEC: 898
SPECIFICATION
HARSH M.C.B. confirm fully to the
latest version of the National / International standards IS 8828-1996,
IEC 898-1995.
DESIGN
Extra cable locks provided in addition to serration to hold cable
firmly. M.C.B. incorporated thermal bimetal for over load protection
and a magnetic coil for protection against short circuit.
FUNCTION OF THERMOSTATIC BI-METAL
It is a composite material comprising of two metallic layers of
different co-efficient of thermal expansion which are permanently
bonded together by pressure welding.
COMPOSITION
Ni-Fe Alloy :
Low co-efficient of thermal expansion
Mg-Cu-Ni-Alloy : Large co-efficient of thermal
expansion
SHORT CIRCUIT PROTECTION
In short circuit, the high current in the range of KA energises
solenoid and a magnetic field is created. Due to this magnetic field
the anchor is pulled down which pushes the plunger to strike the
inner latch, causing instantaneous opening of the contacts
CONTACTS
The Contacts in HARSH M.C.B. are tipped
with special silver graphite alloy, ensuring higher life and maximum
safety against contact welding. Because of low contact resistance
resulting in reduce in voltage drop and low watt loss leading to
energy saving. HARSH MCB have watt
loss figures of 48% to 55% of the specified values leading to energy
saving.
HOUSING
The housing and other moulded components are fire retardant anti
tracking and non hygroscopic. It can withstand high temperature
and is impact resistance.
TRIP FREE MECHANISM
The tripping of the MCB is independent of the position of the knob,
that is to say that while the operating knob may be held in the
ON positions. The MCB will still open in the event of a fault.
CHARACTERISING CURVES
"B" Curves:-Lighting Circuit
Suitable for installation with a steady current. E.g; - electromagnetic
release in circuits like heaters, ovens, geysers, GLS lamps, electric
irons etc. These types are also used for protection of distribution
equipment live wires, cables, metering equipment etc.
"C" Curves: -Motor Circuits
Suitable for high in rush current peaks and which require closer
overhead protection. These include inductive loads as motors, air-conditioners,
transformers, halogen lamps, sodium vapour lamps etc.
BACKUP PROTECTION
HARSH MCB are capable of handling
a very high fault level current u to 10,000 A. However in the event
that the prospective short circuit exceeds the rapturing capacity
of MCB, a perfect co-ordination can be achieved by using suitable
HRC Fuse Link.
CURRENT LIMITING DESIGN
The design of HARSH MCB reduces electro
magnetic stresses and damage to contacts.
Under short circuit condition, even as the current builds up, at
the set value of 7.5 In the magnetic trip takes over and the plunger
forcibly separates the contact and establishes the arc with in 1
millisecond
The arc is then moved in to the arc chamber due to which the arc
voltage rapidly rises and the short circuit current is killed in
3 to 4 milliseconds.
"HARSH" ISOLATOR
Switch disconnectors, for manual operation as a control switch is
available for switching loads in two, three and four-pole versions
current rating are 25 Amps to 63 Amps
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