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Lodestar RPA-SP

Technical specifications

PARAMETER	VALUE
Core Functionality
Types of Protection Functions	three phase overcurrent protection (ANSI 50/51, 3 stages) earth fault protection (ANSI 50N/51N, 2 stages) phase unbalance protection (ANSI 46) thermal overload protection (ANSI 49RMS) inrush current blocking (2nd harmonic restraint) measurement of electrical parameters for the feeder fault and event recording (disturbance recording)
Measurements
Measured Parameters	RMS values of phase currents (Ia, Ib, Ic) phase angles of phase currents
Calculated Parameters	RMS value of zero-sequence current (3I0)
Indication and Control
Indication Elements	7 LEDs for protection function tripping indications mechanical flag indicator 2 LEDs for diagnostics and power supply status LCD display
Control Elements	4 navigation buttons for menu control event reset button
Communication Interfaces	4 navigation buttons for menu control event reset button
Recording Functions	event Log fault Log oscillographic recordings (disturbance recorder)
Signaling and Control Functions
Control	internal capacitive energy storage for controlling a low-power circuit breaker trip
Signaling	2 changeover (Form-C) relay outputs
Parameters
Number of Current Inputs	3
Rated Current of Phase Current Circuits (I_nom), A	5
Phase Current Measurement Range (in secondary values)	0.05 I_nom to 20 I_nom
Current Sensors	3 phase current transformers with a minimum power rating of 10 VA
Power Supply Parameters
Power Supply Options	from current circuits (self-powered) from an auxiliary DC/AC supply
Parameters for Current Circuit Supply	minimum operating current: 0.05 * Inom power consumption: 10 VA
Parameters for Auxiliary Supply	voltage: 220 V (DC or AC, as per version) power consumption: 10 W
Design and Environmental
Operating Temperature Range, °C	standard, from –40 to +70
Ingress Protection (IP) Rating	IP20

MICROPROCESSOR PROTECTION RELAY

The Lodestar RPA-SP is a protection relay designed for substations. It provides relay protection, automation, control, and signaling for step‑down transformers, incoming feeders, and outgoing lines.

The device is available in two power supply versions:

self‑powered – powered from the measured current circuits;
externally powered – powered from an auxiliary power supply.

Control and signaling functions are supported by two relay outputs and one output for a circuit Breaker Trip (MITOP Trip Unit).

Main Functions:

3-phase overcurrent protection.
Earth faults protection.
Unbalance and overload protection.
Harmonic 2 Restraint.
Measured current indication.
Electrical parameter measurement (line/equipment).
Fault event recording.

Benefits:

Data oscillography – records oscillograms even during auxiliary power loss.
Self‑powered operation – works on substations without auxiliary power.
Incoming and outgoing feeder protection – reliable protection for feeder lines.
Step‑down transformer protection – comprehensive transformer protection.
GIS switchgear compatibility – compatible with Schneider Electric RME GIS cells.