Characteristics of MicroLogic Electronic Trip Units

Introduction

MicroLogic electronic trip units provide the following functions:

Protection of the electrical distribution or specific applications
Measurement of instantaneous values and measurement of average values (demand) for electrical quantities
Kilowatt hour metering
Operational assistance such as peak demand, customized alarms, and operation counters
Communication

Identification

Identify the trip unit installed on the circuit breaker by using the four characters on the front face:

	Protection (X)		Case (Y)		Measurements (Z)		Application (T)

	1 2 4 5 6 7	SI LS₀I LS₀IR LSI LSIG LSIR	2 3	ComPact NSX100/160/250 ComPact NSX400/630	– E	No measurement Energy	– G AB M Z AL	Distribution Generator Subscriber Motor 16 Hz 2/3 Alarm
Examples
MicroLogic 1.3	SI		400 or 630 A		–		Distribution
MicroLogic 2.2 G	LS₀I		100, 160 or 250 A		–		Generator
MicroLogic 2.3	LS₀I		400 or 630 A		–		Distribution
MicroLogic 2.3 M	LS₀I		400 or 630 A		–		Motor
MicroLogic 4.2	LS₀IR		100, 160 or 250 A		–		Distribution including trip on earth leakage
MicroLogic 4.3 AL	LS₀I		400 or 570 A		–		Distribution including alarm on earth leakage
MicroLogic 5.3 E	LSI		400 or 630 A		Energy		Distribution
MicroLogic 6.3 E-M	LSIG		400 or 630 A		Energy		Motor
MicroLogic 7.2 E-AL	LSI		100, 160 or 250 A		Energy		Distribution including alarm on earth leakage
MicroLogic 7.3 E	LSIR		400 or 630 A		Energy		Distribution including trip on earth leakage
Type of protection: I Instantaneous L Long-time S₀ Short-time (time delay cannot be adjusted) S Short-time G Ground-fault R Residual (earth-leakage)

MicroLogic Trip Unit Families

The range of MicroLogic trip units is made up of several families:

MicroLogic 1, 2, and 4 without display screen
MicroLogic 5, 6, and 7 with display screen.

On MicroLogic 1, 2, and 4 trip units, the protection functions are set using adjustment dials on the front face of the trip unit:

On MicroLogic 5, 6, and 7 trip units, the protection functions are set:

By using the adjustment dials
By additional settings on the keypad. Setting values are displayed on the screen
Through EcoStruxure Power Commission software.

For more information about the MicroLogic 5, 6, and 7 trip units, refer to DOCA0141EN, ComPact NSXMicroLogic 5/6/7 Electronic Trip Units - User Guide.

In Rating of MicroLogic Trip Units

The In rating (in amps) of a MicroLogic trip unit corresponds to the maximum value of the long-time protection (Ir) setting range for the trip unit. The setting range is indicated on the label on the front face of the trip unit (this label is visible on the front face of the ComPact NSX circuit breaker after the trip unit has been fitted).

Example: MicroLogic 5.2 E 250 trip unit:

Setting range: 100-250 A
In rating = 250 A

Distribution Trip Unit

The following figure and table define the protection functions for distribution-type MicroLogic trip units.

MicroLogic 5 and 6

MicroLogic 7

Item	Parameter	Description		MicroLogic⁽¹⁾
Item	Parameter	Description		2	4	5	6	7
A	–	Trip unit setting range: minimum setting/maximum setting. The trip unit rating In corresponds to the maximum value of the Ir setting range.		O	O	O	O	O
B	Ir	Long-time protection pickup	L	✓	✓	✓	✓	✓
C	tr	Long-time protection time delay	L	O	O	✓	✓	✓
D	Isd	Short-time protection pickup	S	✓	✓	✓	✓	✓
E	tsd	Short-time protection time delay		O	O	✓	✓	✓
F	I²t ON/OFF	Short-time protection I²t curve in ON or OFF position		–	–	✓	✓	✓
G	Ii	Instantaneous protection pickup	I	O	O	✓	✓	✓
H	Ig	Ground-fault protection pickup	G	–	–	–	✓	–
I	tg	Ground-fault protection time delay		–	–	–	✓	–
J	I²t ON/OFF	Ground-fault protection I²t curve in ON or OFF position		–	–	–	✓	–
K	IΔn	Earth-leakage protection pickup	R	–	✓	–	–	✓
L	Δt	Earth-leakage protection time delay	R	–	✓	–	–	✓
(1) Functions: ✓: Adjustable O: Fixed –: Not present

Thermal Memory

The thermal memory is used to simulate temperature build-up and cooling in conductors caused by current variations, according to a time constant. In the event of an overload, the trip units with a thermal memory memorize the build-up temperature caused by the current. Memorizing the build-up temperature leads to a reduction in the trip time.

All MicroLogic trip units incorporate a thermal memory as standard:

For MicroLogic 2 and 4 trip units, the time constant is 15 minutes.
For MicroLogic 5, 6, and 7 trip units, the time constant is 20 minutes.

Motor Trip Units

The following figure and table define the protection functions for MicroLogic type M trip units.

Item	Parameter	Description		MicroLogic type M
Item	Parameter	Description		1.3	2	6 E
A	–	Trip unit setting range: minimum setting/maximum setting. The trip unit rating In corresponds to the maximum value of the setting range.		O	O	O
B	Ir	Long-time protection pickup	L	–	✓	✓
C	Class	Long-time protection trip class	L	–	✓	✓
D	Isd	Short-time protection pickup	S	✓	✓	✓
E	tsd	Short-time protection time delay	S	O	O	O
F	Ii	Instantaneous protection pickup	I	O	O	O
G	Ig	Ground-fault protection pickup	G	–	–	✓
H	tg	Ground-fault protection time delay	G	–	–	✓
–	Iunbal	Phase-unbalance protection pickup		–	O	✓
–	tunbal	Phase-unbalance protection time delay		–	O	✓
(1) Functions: ✓: Adjustable O: Fixed –: Not present

Motor Trip Unit: Additional Protection

MicroLogic type M trip units (in particular MicroLogic 6 E-M) also incorporate additional protection for the motor application. For more information, refer to DOCA0141EN, ComPact NSXMicroLogic 5/6/7 Electronic Trip Units - User Guide..

Indication LEDs

Indication LEDs on the front of the trip unit indicate its operational state.

The LEDs and their meaning depend on the type of MicroLogic trip unit.

Type of MicroLogic trip unit	Description
Distribution	Ready LED (green): Blinks slowly when the electronic trip unit is ready to provide protection. Overload pre-alarm LED (orange): Shows a steady light when the load exceeds 90% of the Ir setting. Overload alarm LED (red): Shows a steady light when the load exceeds 105% of the Ir setting.
Motor	Ready LED (green): Blinks slowly when the electronic trip unit is ready to provide protection. Overload temperature alarm LED (red): Shows a steady light when the motor thermal image exceeds 95% of the Ir setting. The MicroLogic 1.3 M trip unit, which provides short-time protection only, displays the Ready LED (green).

Type of MicroLogic trip unit

Description

Distribution

Ready LED (green): Blinks slowly when the electronic trip unit is ready to provide protection.
Overload pre-alarm LED (orange): Shows a steady light when the load exceeds 90% of the Ir setting.
Overload alarm LED (red): Shows a steady light when the load exceeds 105% of the Ir setting.

Motor

Ready LED (green): Blinks slowly when the electronic trip unit is ready to provide protection.
Overload temperature alarm LED (red): Shows a steady light when the motor thermal image exceeds 95% of the Ir setting.

The MicroLogic 1.3 M trip unit, which provides short-time protection only, displays the Ready LED (green).

The indication LEDs function for circuit breaker load currents:

Above 15 A on a MicroLogic trip unit rated 40 A
Above 30 A on MicroLogic trip units rated > 40 A

The limit value is indicated on the front panel, above the Ready LED of the MicroLogic trip unit.

NOTE: For the MicroLogic 4 and 7 trip units, the protection functions are supplied by a second power supply, in addition to the current transformer supply. The Ready LED blinks irrespective of the load, indicating that the standard protection functions are operational.

To activate the Ready LED when the load current is below the limit value, you can:

Install a 24 Vdc external power supply module which allows the trip unit to be monitored continuously, even when the circuit breaker is open. For more information, refer to LVPED217032EN, ComPact NSX & NSXm Catalogue.
Or, during maintenance visits, connect the pocket battery to monitor the trip unit.

NOTE: If the pre-alarm and alarm LEDs keep lighting up, perform load shedding to avoid tripping due to a circuit breaker overload.

Test Port

MicroLogic trip units feature a test port specifically for maintenance actions.

Use the test port to:

Connect a pocket battery for local testing of the MicroLogic trip unit
Connect the Service Interface for testing, setting the MicroLogic trip unit, updating the MicroLogic firmware, or for installation diagnostics with EcoStruxure Power Commission software
Connect the USB maintenance interface:
- For push-to-trip test or installation diagnostics with the USB maintenance interface stand-alone
- For testing and installation diagnostics, setting the MicroLogic trip unit, updating the MicroLogic firmware with the USB maintenance interface connected to a PC

NOTE: The test port is capped on the ComPact NSX400K circuit breaker.

WARNING
hazard of REDUCED INSULation distances On a ComPact NSX400K circuit breaker, do not remove the cap on the MicroLogic test port. Failure to follow these instructions can result in death, serious injury, or equipment damage.

Interchangeability of MicroLogic Trip Units

Onsite replacement of trip units is simple:

No connections to make
No specific tools (for example, calibrated torque wrench)
Compatibility of trip units provided by mechanical cap
Torque limited screw provides correct torque

The simplicity of the replacement process means that it is easy to make the necessary adjustments as operation and maintenance processes evolve.

NOTE: The screw head is accessible when the trip unit is installed, so the trip unit can still be removed.

NOTE: On ComPact NSX circuit breakers with NA, R, HB1, HB2, and K breaking performances the trip units are not interchangeable.

Sealing the Protection

Seal the transparent cover on MicroLogic trip units to prevent modification of the protection.

On MicroLogic 5, 6, and 7 trip units, it is possible to use the keypad, with the cover sealed, to read the protection settings and measurements.