Instantaneous Overcurrent Protection (I or ANSI 50)

Presentation

Instantaneous protection helps to protect equipment against phase-to-phase, phase-to-neutral and phase-to-ground short circuits. The protection operates with a definite time characteristic. It trips without additional time delay as soon as the setting current is exceeded.

The protection offers two tripping modes, with different breaking times:

Standard mode (when ERMS is not engaged): breaking time of 50 ms, used for applications requiring selectivity. Full selectivity can be provided with any ComPacT NSX or PowerPacT H-, J-, L-frame circuit breaker installed downstream of a MasterPacT MTZ circuit breaker (Refer to selectivity tables for details for Ue ≤ 440 Vac).
Fast mode (when ERMS is engaged): breaking time of 30 ms, typically used for applications where the thermal constraints of the equipment need to be limited and when selectivity is not required. For more information, refer to LVPED318033EN Complementary Technical Information.

NOTE: On MicroLogic Active 2.0, instantaneous protection is based on short-time protection without time setting with standard breaking time of 80 ms.

Availability

Instantaneous overcurrent protection is available on:

MicroLogic Active 2.0, 5.0 and 6.0 control units for IEC standard
3-pole and 4-pole circuit breakers

It is powered by the current flowing through the internal current transformers of the circuit breaker and it does not require an additional external power supply.

Operating Principle

The instantaneous overcurrent protection threshold sets the level of short-circuit current at which the circuit breaker trips with no intentional time delay.

For MicroLogic Active 5.0 and 6.0 control units for IEC standard, instantaneous overcurrent protection can be disabled.

For MicroLogic Active 2.0 control units for IEC standard, instantaneous overcurrent protection cannot be disabled.

Instantaneous overcurrent protection overrides short-time overcurrent protection when the instantaneous overcurrent threshold is adjusted to the same or a lower setting than the short-time overcurrent threshold.

Setting the Protection for MicroLogic Active 2.0

The instantaneous overcurrent protection setting is Ii: instantaneous overcurrent protection threshold (corresponds to a short-time overcurrent protection threshold without time setting).

It can be set as follows:

On the MicroLogic Active pin code-protected display screen, by pressing the Protection Settings button, and selecting the I (instantaneous overcurrent protection) area. See Protection Setting Procedure.
With EcoStruxure Power Commission software (password-protected)
With EcoStruxure Power Device app (password-protected)

Two modes of configuring the protection settings are available:

Quick setting mode is used to configure quick protection settings
Fine adjustment mode is used to configure fine protection settings

Quick Protection Settings for MicroLogic Active 2.0

Quick protection settings are available:

On the MicroLogic Active HMI
With EcoStruxure Power Device app

Setting	Unit	Values	Factory setting
Ii	A	OFF, (1.5 / 2 / 2.5 / 3 / 4 / 5 / 6 / 8 / 10) x Ir	1.5 x Ir

For more information, refer to the setting guidelines.

Fine Protection Settings for MicroLogic Active 2.0

Fine protection settings are available:

On the MicroLogic Active HMI
With EcoStruxure Power Commission software
With EcoStruxure Power Device app

Setting	Unit	Range	Step	Factory setting
Ii	A	1.5–10 x Ir	0.1 x Ir	1.5 x Ir

For more information, refer to the setting guidelines.

Protection Characteristics for MicroLogic Active 2.0

Characteristic	Unit	Standard value	ERMS value
Breaktime at 2 x Ii threshold	ms	≤ 80	≤ 80
Non-tripping time	ms	> 20	> 20
Accuracy on threshold	%	+/- 10	+/- 10

Setting the Protection for MicroLogic Active 5.0 and 6.0

Instantaneous overcurrent protection for MicroLogic Active 5.0 and 6.0 can be enabled or disabled with EcoStruxure Power Commission software.

The instantaneous overcurrent protection setting is Ii: instantaneous overcurrent protection threshold.

It can be set as follows:

On the MicroLogic Active pin code-protected display screen, by pressing the Protection Settings button, and selecting the I (instantaneous overcurrent protection) area. See Protection Setting Procedure.
With EcoStruxure Power Commission software (password-protected)
With EcoStruxure Power Device app (password-protected)

Two modes of configuring the protection settings are available:

Quick setting mode is used to configure quick protection settings
Fine adjustment mode is used to configure fine protection settings

Quick Protection Settings for MicroLogic Active 5.0 and 6.0

Quick protection settings are available:

On the MicroLogic Active HMI
With EcoStruxure Power Device app

Setting	Unit	Values	Factory setting
Ii	A	OFF, (2 / 3 / 4 /6 / 8 / 10 / 12 / 15) x In	2 x In

For more information, refer to the setting guidelines.

Fine Protection Settings for MicroLogic Active 5.0 and 6.0

Fine protection settings are available:

On the MicroLogic Active HMI
With EcoStruxure Power Commission software
With EcoStruxure Power Device app

Setting	Unit	Range	Step	Factory setting
Ii	A	2.0–15 x In	0.1 x In	2.0 x In

For more information, refer to the setting guidelines.

Protection Characteristics for MicroLogic Active 5.0 and 6.0

Characteristic	Unit	Standard value	ERMS value
Breaktime at 2 x threshold	ms	≤ 50	≤ 30
Non-tripping time	ms	> 20	0
Accuracy on threshold	%	+/- 10	+/- 10

Predefined Events for MicroLogic Active 2.0, 5.0 and 6.0

The function generates the following predefined events:

Code	Event	History	Severity
0x6402 (25602)	Instantaneous (Ii) trip	Trip	High
0x0C08 (3080)	Ii protection disabled	Protection	Low

Predefined events cannot be modified by the user. For general information about events, refer to Event management.

The trip event is generated when the circuit breaker tripping voltage release (MITOP) activates.

Predefined Events for MicroLogic Active 5.0 and 6.0

When instantaneous overcurrent protection is disabled, the following event is generated

Code	Event	History	Severity
0x0C08 (3080)	Ii protection disabled	Protection	Low

Recommended Actions

Code	Event	Recommended actions
0x6402 (25602)	Instantaneous (Ii) trip	Reset the circuit breaker. See Resetting a Trip Event.
0x0C08 (3080)	Ii protection disabled	No action required. For information only.

Resetting a Trip Event

For information about resetting the circuit breaker after a trip due to an electrical fault, refer to the relevant document:

MasterPacT MTZ1 IEC Circuit Breakers with MicroLogic Active Control Unit - User Guide
MasterPacT MTZ2/MTZ3 IEC Circuit Breakers with MicroLogic Active Control Unit - User Guide