Circuit Breakers


iUCB-DC48XX Single Pole Intelligent Remote-Controlled Uni-directional Resettable Electronic Circuit Breaker up to 25A, 48VDC, 1.5kW

iBCB-DC48XX 3-Pole Intelligent Remote-Controlled Bi-directional Resettable Electronic Circuit Breaker up to 25A, 48VDC, 4.5kW


An IRCB is an intelligent solid state over-current/over-voltage protection and switching device with an extremely short connect/disconnect interval of less than 1,5 µs. It is designed for use in power supply, power distribution, battery management and industrial control applications.

It's solid state design makes it specially useful in hazardous industrial environments such as, grain mills, coal mines, oil and gas processing enterprises, etc. Space, aviation and medical applications are also targeted for the safety reasons particularly with low voltage AC versions of the IRCB.

The IRCB proactively monitors and controls a pass current within a power path to dynamically prevent sudden voltage over-runs, drops, and current spikes on a power supply line where high in-rush consuming loads are instantly activated or de-activated.

Power system destruction is prevented through a dynamic over-current limiter and fault detection circuit breaker, should a short circuit condition occur within a powered load.

The IRCB provides the capability to pre-set rapid/soft start/stop current supplied to the load according to the demands of the application. In addition, it contains the ability to automatically re-start after the clearance of an abnormal condition. With the ability to be remotely controlled, the IRCB also serves in applications as a solid-state relay. The remote control capability contains a means of continuously reporting its operational state.

Its use eliminates a number of undesirable phenomena inherent in electric networks caused by the following:
1 The majority of electric loads have high in-rush currents. Their amplitudes may reach the level of a short circuit condition, and their duration depends both on input impedance of the load and on output impedance of a power source
2 The activation of a high in-rush current load results in a sharp current spike and a large voltage drop on a common power supply output bus. This condition can disrupt surge-sensitive circuits within other loads
3 A short-circuit condition within one powered load results in a disruption of steady-state power to all other loads on the bus. The over-current condition resulting from the short circuit introduces possible damage to components within the power distribution system. In such case, the faulty load should be immediately disconnected from the distribution network to prevent a total system failure
4 Steady power delivery to other loads on the bus is impossible until the faulty load has been identified and removed from the system. This procedure may take a substantial amount time
5 Resuming steady power delivery to a bus or system with all the loads connected and with all their in-rush currents being simultaneously summed results in an over-current surge at the power supply output
6 Fuses, or heat-sensitive re-settable circuit breakers, both mechanical and solid-state, may withstand high in-rush currents but have a major disadvantage in that they break-off during short circuit conditions. The protective actions of these devices are excessively slow due to the conductive properties of the molten and evaporated metal particles within a fuse during its break-down, and the conductive properties of ionized air within an electric spark between the breaking mechanical contacts
7 With a power source impedance of less than 0,01 Ohms, the peak current values of in-rush and short-circuit conditions may destructively overcome the maximum operational current of devices in the power system. To compensate for this potential, the overload protection required results in increased size and weight of the re-settable protection components
8 The main power source should be designed to support an overload potential of peak output currents 10-15 times greater than the steady-state value. This results in increased size, weight and cost for the whole power supply and distribution system, and particularly concerns the AC/DC and the DC/DC power conversion devices
9 All power distribution systems exhibit power losses within the system. These losses usually are the result of voltage drops across the commutation and protection components due to multiple junction contacts. The junction contacts also substantially reduce a power systems reliability
10 In "critical" applications, electronic equipment must remain operational through any power source interruption. These systems employ multiple power sources to maintain non-stop operation. Power control switches within these "critical" applications are required to support different voltage sources with possible different polarities and, possibly, of different values. Restrictive physical properties prevent conventional fast-acting solid-state devices from being employed as commutation/protection switches in such "critical" applications because of these potential variations in power sources


Taking the above drawbacks into account, IRCB devices exhibit a number of advantages in power system design.

An iUCB-DC48 (uni-directional DC) version is designed to satisfy the bulk of the conventional DC power fed electronic applications providing stable polarity of voltage across the controllable switch.

An iBCB-DC48 (bi-directional DC) version is designed to satisfy the "critical" electronic applications providing alternating polarity of voltage across the controllable switch.

An iSCB-AC36 (single-pole AC) version is designed to satisfy the bulk of the conventional low voltage AC power fed electronic applications seeking both random and zero-crossing switching modes.

An iMCB-AC36 (multi-pole AC) version is designed to satisfy the multi-line low voltage AC power fed electronic applications seeking both random and zero-crossing switching modes. All versions contain a controllable solid-state switching structure (C4S) connected in-series as part of the monitored/protected current path, and a control circuit to monitor the current flow, and drive the C4S.

A unique feature of the iBCB-DC48 version is that its C4S allows current flow in either direction of the monitored/protected current path while in the on/conducting state without regard to the polarity of the applied voltage. The iUCB-DC48, iBCB-DC48, iSCB-AC36 and iMCB-AC36 contain the following advanced features:

  • Customized pre-set capability for maximum steady-state operation value of pass current
  • Customized pre-set capability for start and break procedures for normal operations, and fault conditions
  • Fast-Action (less than 1,5 µs) OFF-ON transition for rapid turn-on
  • Fast-Action (less than 1,5 µs) ON-OFF transition for rapid turn-off
  • Gradual (about 300 µs) OFF-ON transition for a soft turn-on , i.e. gradual increase of current supplied to the load
  • Gradual (about 300 µs) ON-OFF transition for a soft turn-off, i.e. gradual decrease of current supplied to the load
  • For an over-current surge condition, the IRCB acts fast (less than 50 ns) to limit the current surge to less than 50% over the maximum steady-state operation value; the IRCB then further drives the pass current to a pre-set protection level of less than 30% over the maximum steady-state operation value
  • For up to 5 ms, the IRCB sustainably experiences the abnormal condition of over-current limited to less than 30% over the maximum steady-state operation value
  • A circuit break will occur if the limited over-current condition exceeds 5 ms
  • Upon expiry of an over-current condition within less than 5 ms, the device will be turned on to resume steady-state operation
  • For over-voltage/under-voltage conditions, a circuit break occurs if the over-voltage/under-voltage condition exceeds 10 µs
  • During over-temperature condition, a circuit break occurs until the C4S temperature falls below a pre-set value
  • The device automatically re-starts after any abnormal condition is removed
  • The device has remote control and real-time state reporting
  • The device is self-powered by a host power source of a protected network, or (additional option for iBCB-DC48 version) by a separate power supply
An incrementing control circuit provides the ability to start the pass current limitation process prior to an in-rush current or short-circuit current value reaches the pre-set protection level.

FIG. 1 illustrates an in-rush current limitation and a pass current gradual increase during a soft turn-on procedure performed by the IRCB device.


Fig. 1 - Soft Turn-On & In-Rush Current Limitation


To soft start power to the load, the resistance of the C4S decreases gradually from several Mega-Ohms at the off/non-conducting state to several milli-Ohms at the on/conducting state.
Such a soft-start switching procedure establishes a low rate-of-increase of pass current within the monitored/controlled path. This capability substantially reduces in-rush current spikes.

Due to the soft turn-on facility, the rate-of-increase of the in-rush current through the monitored/controlled path is also substantially reduced, therefore, substantially eliminating commutation voltage drops, spikes, current surges and EMI.

FIG. 2 illustrates an over-shot fluctuation of pass current and an over-current limitation procedure performed by the IRCB device.


Fig. 2 - Over-Current Surge Limitation


As an over-current surge occurs, a rate-of-increase of pass current within the monitored/controlled path is actively reduced proportionally to that of the surge.

Therefore, in less than 50 ns a pass current over-shot is limited at a level of less than 50% over the maximum steady-state operational value. The pass current is driven to a pre-set protection level of less than 30% over the maximum steady-state operational value.

If the over-current condition ceases in less than 5 ms, the IRCB device resumes steady-state power to the load.

If the over-current condition exceeds 5 ms, the IRCB device initiates a circuit break procedure which may be pre-set either as a rapid or soft turn-off as required by the application.

FIG. 3 illustrates a short circuit current limitation and a circuit break procedure performed by the IRCB device.


Fig. 3 - Short-Circuit Current Limitation & Emergency Break-Off


As a short circuit condition occurs, a rate-of-increase of pass current within the monitored/controlled path is sharply suppressed proportionally to that of a shortage over-shot.

Consequently, in less than 50 ns a pass current over-shot is allowed to reach a level of less than 30% over the maximum steady-state operation value. The pass current is actively regulated to a pre-set protection level of less than 30% over the maximum steady-state operation value.

If the over-current condition ceases in less than 5 ms, the IRCB device restores steady-state power to the load

If the over-current condition exceeds 5 ms, the IRCB device initiates a circuit break procedure which may be pre-set either as rapid or soft turn-off as required by the application.

As any abnormal condition ceases, the IRCB device initiates an automatic re-start procedure to return power to the load.
Based on the above information, the further benefits may outflow from this technology:
  • Provision of very smooth current commutation to high in-rush loads and the elimination of in-rush current spikes
  • Elimination of short-circuit current surges
  • Improved power distribution system over-current protection
  • Improved power provision reliability
  • Improved quality of power supplied to multiple randomly activated loads
  • Reduced weight, size, power consumption and power losses inherent in commutation/protection hardware