Measurement Function

Instantaneous RMS Measurements

The MicroLogic trip unit continuously displays the RMS value of the highest current of the three phases and neutral (Imax). The navigation buttons can be used to scroll through the main measurements.

In the event of a fault trip, the trip cause is displayed.

The MicroLogic A trip unit measures phase, neutral, and ground fault currents.

MicroLogic P/H trip units offer voltage, power, power factor, frequency, and cos ? in addition to the measurements provided by MicroLogic A trip units.

Maximum / Minimum Ammeter

Every instantaneous measurement provided by MicroLogic A trip units can be associated with a maximum/minimum ammeter. The maximum for the highest current of the three phases, neutral, and demand current can be reset using the FDM display unit or the communication system.

Energy Metering

The MicroLogic P/H trip units also measures the energy consumed since the last reset of the meter. The active energy meter can be reset using the MicroLogic trip unit keypad, the FDM display unit, or the communication system.

Demand and Maximum Demand Values

MicroLogic P/H trip units also calculate demand current and power values. These calculations can be made using a block or sliding interval that can be set from five to sixty minutes in steps of one minute. The window can be synchronised with a signal sent through the communication system. Whatever the calculation method, the calculated values can be recovered on a PC through the communication network.

Ordinary spreadsheet software can be used to provide trend curves and forecasts based on this data. They provide a basis for load shedding and reconnection operations used to adjust consumption to the subscribed power.

Power Quality

The MicroLogic H trip unit calculates power quality indicators taking into account the presence of harmonics up to the fifteenth harmonic, including the total harmonic distortion (THD) of current and voltage.

MicroLogic A/P/H Trip Units Integrated Power Meter Functions

MicroLogic A/P/H Integrated Power Meter Functions			Type	Display
MicroLogic A/P/H Integrated Power Meter Functions			Type	MicroLogic LCD	FDM Display
Display of protection settings
Pick-ups (A) and delays	All settings can be displayed	Ir, tr, Isd, tsd, Ii, Ig, tg	A/P/H	X	—
Measurements
Instantaneous rms measurements
Currents (A)	Phases and neutral	I_A, I_B, I_C, I_N	A/P/H	X	X
	Average of phases	Iavg = (I_A + I_B + I_C) / 3	A/P/H	—	X
	Highest current of the 3 phases and neutral	Imax of I_A, I_B, I_C, I_N	A/P/H	X	X
	Ground fault (MicroLogic 6)	% Ig (pick-up setting)	A/P/H	X	X
	Current unbalance between phases	% Iavg	P/H	—	X
Voltages (V)	Phase-to-phase	VAB, VBC, VCA	P/H	X	X
	Phase-to-neutral	V_AN, V_BN, V_CN	P/H	X	X
	Average of phase-to-phase voltages	Vavg = (V_AB + V_BC + V_CA) / 3	P/H	—	X
	Average of phase-to-neutral voltages	Vavg = (V_AN + V_BN + V_CN) / 3	P/H	—	X
	Ph-Ph and Ph-N voltage unbalance	% Vavg	P/H	—	X
	Phase sequence	ABC, ACB	P/H	X	XFDM121 only.*
Frequency (Hz)	Power system	f	P/H	X	X
Power	Active (kW)	P, total P, per phase	P/H P/H	X X	X X
	Reactive (kVAR)	Q, total Q, per phase	P/H P/H	X X	X X
	Apparent (kVA)	S, total S, per phase	P/H P/H	X X	X X
	Power Factor	PF, total PF, per phase	P/H P/H	X X	X X
	Cos φ	Cos φ, total Cos φ, per phase	P/H P/H	X X	X X
Maximum/Minimum Ammeter	Associated with instantaneous rms measurements	Reset using the FDM display unit and MicroLogic keypad	A/P/H	X	X
Energy Metering
Energy	Energy Active (kW), reactive (kVARh), apparent (kVAh)	Total since last reset	P/H	X	X
Demand and Maximum Demand Values
Demand Current (A)	Phases and neutral P	Present value on the selected window Maximum demand since last reset	P/H P/H	X X	X X
Demand Power	Active (kWh), reactive (kVAR), apparent (kVA)	Present value on the selected window Maximum demand since last reset	P/H P/H	X X	X X
Calculation Window	Sliding, fixed or com-synchronised	Adjustable from 5 to 60 minutes in 1 minute steps*	P/H	—	—
Power Quality
Total Harmonic Distortion (%)	Of voltage with respect to rms value	THDU,THDV of the Ph-Ph and Ph-N voltage	H	X	X
Total Harmonic Distortion (%)	Of current with respect to rms value	THDI of the phase current	H	X	X