Multifunctional three phase voltage monitoring relay RNPP-302 is designed to protect three-phase consumers from major electrical network failures, such as:

• Voltage deviation beyond permissible limits
• Phase sequence errors and phase sticking
• Phase failure and voltage asymmetry

RNPP-302 measures the actual phase (line-to-line) voltages in networks with a grounded or isolated neutral and controls the coil of an external magnetic starter that switches the load power circuit.

The relay also monitors the state of the power contacts of the external magnetic starter before and after the load is activated, ensuring their reliability (e.g., detecting contact welding or sticking). 

The device operates in four independent modes:

• Phase-failure relay (voltage-level control disabled)
• Minimum voltage relay
• Maximum voltage relay
• Voltage relay

RNPP-302 displays the actual phase (line-to-line) voltage, voltage fault conditions, the load relay state (on/off), and the type of fault.

Advantages:

• Connection via a magnetic starter
• Monitoring the state of the starter's power contacts before and after load activation
• Segment display
• Support for networks with grounded or isolated neutral
• Ability to operate in four independent modes

Applications:

• Monitoring phase and line-to-line voltages in a three-phase network
• Protecting three-phase or, in some cases, single-phase equipment from three-phase network faults, such as voltage faults, incorrect phase sequence, phase sticking, phase failure, and voltage asymmetry
• Protecting three-phase equipment in three-phase networks without a neutral wire

Key Features:

• Monitoring the allowable level of actual phase/line-to-line voltage
• Phase sequence and phase sticking control
• Monitoring phase integrity and network voltage symmetry
• Monitoring the state of the magnetic starter's power contacts before and after load activation
• Disconnecting the load by opening the magnetic starter coil circuit in response to fault conditions, with user-configurable trip delay
• Monitoring network voltage quality after load disconnection and automatic load reconnection once voltage parameters are restored, with user-defined automatic restart time
• Visual indication of all types of network voltage faults and magnetic starter contact switching failures