Setting Up the Metering Functions

Prior to setting up the protection functions or carrying out measurements, set up the following parameters of the MicroLogic trip unit:

System type
Calculation mode for the demand current
Calculation mode for the demand power
Power factor sign convention

Selecting the System Type

The MicroLogic P trip unit offers three measurement options, as indicated in the table. The availability of measurements depends on the option selected.

Measurement type	Currents on phases I1, I2, I3	Current on neutral IN	Phase-to-phase voltages U12, U23, U31	Phase-to-neutral voltages V1N, V2N, V3N
3 phases, 3 wires, 3 CTs (method using two wattmeters)	✔	–	✔	–
3 phases, 4 wires, 3 CTs (method using three wattmeters)	✔	–	✔	✔
3 phases, 4 wires, 4 CTs (method using three wattmeters)	✔	✔	✔	✔

NOTE: It is advised not to use the 3-phase, 4-wire, 4-CT type of measurement unless the neutral is effectively connected to the trip unit (four-pole circuit breaker with an external voltage-measurement input).

Step

Action

Press . The History, Maintenance and Setup menu opens.

Press to select Metering setup

Press . The Metering setup menu opens.

Press to select System type.

Use the navigation buttons to access and set the System type.

Press to confirm the selection.

NOTE: The neutral current IN cannot be measured with the 3-phase, 3-wire, 3-CT and 3-phase, 4-wire, 3-CT types.

For a 3-pole device, the neutral, if distributed, must be connected to terminal VN of the MicroLogic P trip unit.

For more information about types of measurements, refer to Measurements.

Selecting the Calculation Method for Demand Current

Step	Action
1	Press . The History, Maintenance and Setup menu opens. Press to select Metering setup
2	Press . The Metering setup menu opens. Press to select Current demand.
3	Press . The Current demand menu opens.
4	Use the navigation buttons to access and set the Calculation method. Thermal Block interval NOTE: The thermal method is based on l²t calculation. Press to confirm the selection.
5	Use the navigation buttons to access and set the Window type. sliding fixed Press to confirm the selection.
6	Use the navigation buttons to access and set the Interval (5 to 60 minutes in 1 min steps). Press to confirm the selection.

Selecting the Calculation Method for Demand Power

Step	Action
1	Press . The History, Maintenance and Setup menu opens. Press to select Metering setup
2	Press . The Metering setup menu opens. Press to select Power demand.
3	Press . The Power demand menu opens.
3	Use the navigation buttons to access and set the Calculation method. Thermal Block interval NOTE: The thermal method is based on I²t calculation. Press to confirm the selection.
4	Use the navigation buttons to access and set the Window type. sliding fixed Sliding window: Power demand is refreshed every 15 seconds. Fixed window: Power demand is refreshed at the end of the time interval. Press to confirm the selection.
5	Use the navigation buttons to access and set the Interval (5 to 60 minutes in 1 min steps). Press to confirm the selection.

NOTE: The synchronization function Synchro.Com is available only with the COM communication option. With this function, the demand power is determined on the basis of a signal synchronized by the communication module.

Setting Up the Power-Factor Calculation

Step

Action

Press . The History, Maintenance and Setup menu opens.

Press to select Metering setup

Press . The Metering setup menu opens.

Press to select Sign convention.

Use the navigation buttons to access and set the Sign convention.

IEEE
IEEE alt
IEC

Press to confirm the selection.

For more information, refer to Power Factor Sign Conventions .