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EntelliGuard* L

Protection of standard circuits

Protection of standard circuits EntelliGuard Air Circuit breakers
Protection devices as the EntelliGuard Air Circuit breaker are To protect standard circuits, the breakers are equipped with
used in a wide variety of environments to protect conductors, a number of protection devices.
equipment and devices in low voltage distribution circuits. To
use this product to its full potential, it is necessary to verify
that it functions correctly in the environment in which it is Overload protection device
used, and that it meets the electrotechnical requirements of First highly accurate menu driven overload protection device
the circuit it protects. that has an adjustment range of 0.4 to 1 x the breaker rating.
in thirteen steps.
This device is normally set to a value that is equal or closely
Application Guide environment and fully complies with the environmental Timed short-circuit protection device
Environment
matches the design current (Ib).
EntelliGuard will function well in almost any industrial
requirements of the relevant EN60947-2 standard.
Set as a multiple of the overload adjustment. This device
offers a broad adjustment range of 1.5 to 12.
The setting of this device depends on several parameters:
Maximum short-circuit current
- inrush characteristics of the protected devices
Each protective device must be capable of interrupting
the maximum short-circuit current at the point where it
- fault currents to earth
is installed (see HD384 standard). The interruption ratings
17 narrow and accurate time bands allow the EntelliGuard Air
(Breaking Capacities) of the EntelliGuard circuit breaker can - protection against the weakest short-circuit current
Circuit Breaker to interrupt a fault within the timing required
be found on page 3 of this catalogue. by the standards. to offer selectivity across multiple levels
Intro and allow the user to take inrush currents into account.
Design current of a circuit
The equipment and devices in an electrical circuit determine Ground fault protection
A its current load or design current (Ib). It is possible to combine two devices to detect fault currents
A circuit breaker’s overload or Ir setting is normally adjusted to earth. They can be set as a multiple of the value of the
to a value equal to the design current. current sensors mounted in the breaker and have a broad
B adjustment range of 0.2 to 1 times the breaker rating.
Weakest short-circuit current in a circuit The first is a residual device that takes the sum of the current
On a short-circuit event, the total circuit impedance in three phases and neutral. If this is no longer equal to zero it
C determines both the MAXIMUM and WEAKEST short-circuit sends an alarm or trips the breaker.
current that can flow in the circuit.
The second allows the user to measure the return current
For the weakest short circuit current, it is necessary to running between the earth leg and neutral. On detecting a
D establish if the protection device trips before the electrical fault to earth, the device sends an alarm, or trips the breaker.
conductors reach their maximum temperature, this for
operating times of 0.1 to 5 seconds. 14 narrow and accurate time bands allow the EntelliGuard Air
E Circuit Breaker to interrupt a fault within the timing required

Fault currents by the standards and offer selectivity across multiple levels.
In the 2005 edition of the IEC60364-4-41 the general
X terminology, ‘Protection against Electrical shock’ has been Instantaneous short-circuit protection
adapted whilst two new terms have been introduced: Set as a multiple of the primary overload adjustment Ie this
device offers a broad adjustment range of 2 to 15.
1) Protection under normal conditions now designated:
Basic protection This device is normally used to limit the time that higher
short-circuit currents can run in the protected circuit. Whilst
2) Protection under fault conditions now designated: the timed short-circuit protection device waits for a set time,
Fault protection the instantaneous device immediately trips the breaker once
the set value is reached.
Fault protection being provided by protective equipotential
bonding and automatic disconnection of the supply. Under The device used in the EntelliGuard Air Circuit Breaker
fault conditions, depending on the network an interruption maintains selectivity by only reacting to the 2nd half wave
time of 5 seconds (TN) or 1 second is required (TT) for circuits of a short-circuit current and uniquely allows the use of the
with a rating >32A. Depending on the configuration of the ‘Zone Selective Interlock’ feature.
earthing system, the 1 and 5 second disconnection time is
also required for interruption of a second fault in IT systems.

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