Automatic Circuit Breaker

Portex Technologies is India’s first and only manufacturer of Automatic Circuit Breakers. Our R&D team of highly dedicated and compete engineers have developed this Automatic Circuit Breaker due to the high demand from the electrical and electronics industry.

This circuit breaker operates on the principle of a bimetallic switch. The current carrying bi-metal strip senses over current and actuates a beryllium copper blade which snaps open the contacts and interrupts the current. After some time delay the bimetal cools down and the contacts snap close. The snap action opening and closing of contacts ensures that there is no sparking during the make and break switching. These contacts are made of solid silver and have a very long life. The outer body is cylindrical in shape and has a small size due to which it can be easily fitted in any device or instrument. It can also be mounted on a PCB. The body is made of solid fiber glass to ensure high strength and rigidity and it is electrically insulated, so there is no chance of current leakage or electrical shock. The body is epoxy sealed and so the operating characteristics are unaffected by moisture, dust, dirt, fumes, etc.

Special Features

  • India’s first and only Automatic Circuit Breaker
  • Small size, easily mountable on PCB or any instrument
  • Snap action make and beak switching
  • No sparking or chattering
  • Solid silver contacts for long life of 1,00,000 operations
  • Available for current ranges from 1A to 6A
  • Technical Specifications
  • Automatic Circuit Breaker Dimensions

Rated Voltage Upto 250 VAC or 24 VDC
Rated Current 1A to 8A in increments of 0.5A
Maximum Load Switching Capacity 30 AMPS
Switching Action SPST Normally Closed (N.C.) contacts which open with a snap action at fault condition.
Flash-over Voltage Exceeds 2 KV between body & leads.
Endurance (Life) Exceeds 100,000 operations (trippings).
Restart Mode Automatic restart after time delay. Adequate precaution must be exercised in applications where automatic restart can cause injury, i.e., power tools, mixie blade, power saws, machinery etc.

Miniature Circuit Breaker | Push Button Circuit Breaker

Miniature Circuit Breaker-cum-ON/OFF Switch

Miniature Circuit Breaker – Snap fit

Miniature Circuit Breaker – Screw in

PORTEX-Precision is a miniaturized precision thermal circuit breaker with a ROCKER actuated ON/OFF switch. This provides the dual benefits of operating the it as a regular ON/OFF switch as well as an overload circuit breaker for the protection of equipment.

It is connected in series with the load and protects against over-current caused by any fault condition in the circuit or equipment, overload, misuse, voltage fluctuation, etc., by tripping and breaking supply when amps. load increases beyond maximum specified limit.

This Circuit Breaker is Patented in India and is fully designed, developed and manufactured in India. No Chinese components have been used.

Operating Mechanism: It has a reliable over-centre trip mechanism, actuated by a separate bimetallic heater system, housed in an insulated compartment. This design results in minimal heat loss and fast sensing of over-current, thereby, ensuring extremely rapid and accurate overload performance and complete safety during fault conditions. In the event of an overload, the normally closed contacts open with a “snap action” to interrupt the current, and the ON/OFF rocker switch moves to the OFF position. Pressing this ON/OFF rocker switch to the ON position resets the over-centre trip mechanism and restores the supply.

Push Button Circuit Breaker

Push Button Circuit Breaker

PORTEX Single Button Circuit Breaker is a single pole, precision thermal circuit breaker with a push to reset button on top. This circuit breaker has a threadneck panel mounting arrangement which can be fitted in any 9mm hole with the plastic knurled nut.

Operating Mechanism:

It is the same as the Rocker Actuated Circuit Breaker. The contacts open and close with a “snap action”. The push button clearly extends out when the circuit breaker trips and pressing it resets the trip mechanism and restores the supply.

Special Features:

  • Rocker ON/OFF switch cum over-current protection Circuit Breaker
  • Specially designed to work in low ampere conditions
  • Can be fitted in any switch board cavity to replace a normal ON/OFF switch
  • Easy installation with two screws or push-fit mounting without screws
  • Snap action opening and closing of contacts without chattering or sparking
  • Minimal heat loss, accurate and precise operation
  • Due to manual restarting, operator has to rectify fault before switching ON
  • Non-tamperable, factory pre-set calibration, cannot be altered
  • Available current rating from 1A to 20A in increments of 0.5A

ADVANTAGES of MINIATURE THERMAL circuit breaker over MCB type circuit breaker

  Portex Miniature Circuit Breaker MCB type Circuit Breaker Why Portex-Precision is superior
Designed for Dual Function Specially designed dual function device which can be used as a regular ON/OFF switch as well as an overload protection switch.
Longer Life with Special Switching Mechanism Specially designed for continuous use as a manual switch, over a long period of time. MCB type circuit breaker get damaged very quickly after repeated usage.
Extremely Reliable and Accurate Thermal Operating Mechanism Specially designed for minimal heat loss due to insulated heater compartment for the bimetal, thereby, providing a very reliable and accurate thermal operating mechanism. Once calibrated for a rated ampere load, this device always trips within 20% overload current. Heat loss in MCB circuit breakers makes them extremely unreliable, sometimes not even tripping at 50% overload current
Designed for Extremely Low Current Ratings Specially designed for very low current ratings of 0.5A, 1A, 1.5A, 2A, 2.5A, in increment of 0.5A till 20A. The lowest MCB current rating available is 6A.
Greater Accuracy in Precision Controls PORTEX-Precision circuit breakers operate within overloads of 20%. Throughout the world, the industry standards of various manufacturers of thermally operated circuit breakers specify a “must trip” point of 35% overload or more. In comparison, our devices are calibrated to carry rated current continuously but “must trip” within an overload of 1% to 20% at 30 degrees C ambient temperature.
Increased Reliability due to no Mechanical Latching Specially designed with no mechanical latching for holding the contacts in the closed position. The contacts stay in the closed position due to the over-centre mechanism, which snaps open the contacts when the bimetal heats up and changes the over-centre angulation. Hence, the problems of unreliability due to latch wear-out and change in latch release characteristics due to friction are eliminated. Mechanical latching in MCB circuit breakers makes them extremely unreliable.

Illustrative list of Applications

  • Protection of all industrial, commercial and domestic equipment against excessive amps. load.
  • Motors, pumps, electrically driven equipment, appliances etc. protection against over-current due to overload, stalling, low or high voltage, failure to start, locked rotor, single phasing etc.
  • All power supply equipment, e.g., UPS, Invertors, SMPS Power supply, Voltage Stabilizers, etc.
  • Business Machines
  • Lab Equipment
  • Computers
  • Battery Chargers
  • Instrumentation
  • Machine Tools
  • Industrial Machinery
  • Medical Equipment
  • Power Tools
  • Industrial Electronics
  • Testing Equipment
  • Generators

Tripping Characteristics of Miniature Circuit Breaker

Portex precision circuit breakers are thermally operated devices fitted with a bi-metal actuated tripping mechanism which function upon deflection of the bi-metal when it heats due to increased amps load. Several unique patented design features in our devices prevent dissipation of heat generated in the bi-metal, which is contained in a chamber. This results in increased sensitivity and consistent accuracy of trip current load.

As a result, Portex circuit breakers have the following tripping characteristics:

1. Tripping takes place within an overload of 5% to 20% of the maximum continuous current rating. For example, if the maximum continuous load is 10 amps., then the circuit breaker will not trip up to 10.5 amps., (i.e. 10A + 5% overload of 10A = 10.5A), at an ambient temperature of 30C, but will definitely trip at a load of 12 amps. or less, (i.e. 10A + 20% overload of 10A = 12A). All circuit breakers of other manufacturers internationally operate within an overload of 35% as compared to an overload of 20% for Portex circuit breakers.

2. Since our circuit breakers are also designed to not trip at 5% current overload, i.e., they will hold and operate continuously at up to 5% overload of the rated current. This ensures that there is no nuisance tripping due to starting loads, in-rush currents, short duration overloads, starting surges or other short duration voltage fluctuations and load variations, which are self correcting and do not damage the equipment.

3. The time take to trip will depend upon 3 factors as follows:

Severity of Overload: With increased amps. load, the time taken to trip reduces, i.e. higher the overload, lesser the tripping time. Continuous slight overload will result in extended tripping time.

Cold Condition: At cold condition, i.e., when the circuit breaker is switched on and the initial starting current is at 20% overload, then the tripping time will be longer as the bimetal has to heat up from cold condition.

Hot Condition: At hot condition, i.e., when the circuit breaker is already operating at the normal load current and then current increases to 20% overload, the tripping time will be short as the bimetal is already running hot.

4. In both the cold and hot condition, the trip current remains the same. Only the tripping time will be more when switched on from cold condition as compared to hot condition.

5. Data on the relationship between trip time and load, indicating upper and lower limits of tolerance within which the devices operate is presented in the below graph.

Tripping Time vs Current Graph

Miniature Circuit Breaker – Screw-in Dimesions

Miniature Circuit Breaker – Snap-fit Dimensions

Push Button Circuit Breaker Dimensions

Technical Data

 Rated Voltage  Any voltage up to 250 VAC/48 VDC
 Rated Current Range  0.5A to 20A in increments of 0.5A
 Interrupting Capacity (Maximum)  6 times standard current rating
 Switching  Single Pole Single Throw snap-action
 Endurance  Exceeds 10,000 trippings at 200% rated load
 Dielectric Strength   1500 VAC
 Insulation Resistance  100 megohm
 Ambient temperature  -20…+70 °C (-4…+158 °F)