Basler UF 312 Under Frequency Protective Module

The Basler UF 312 is an under‑frequency protective module designed to detect and respond to frequency decays in electrical power systems. It is part of Basler Electric's protective relay family and is identified by part number 9094700100. The module monitors system frequency and initiates a trip or alarm when the frequency falls below a preset threshold, helping to prevent generator overspeed, equipment damage, and system instability.

Key Features

The UF 312 offers adjustable frequency trip settings from 45 to 60 Hz, with independent time delay adjustment from 0.1 to 10 seconds. It features a high‑accuracy frequency sensing circuit with minimal drift over temperature. The module provides both normally open and normally closed output contacts for tripping breakers or activating alarms. Front‑panel LEDs indicate power, frequency status, and trip conditions.

Technical Specifications

Input voltage: 120 VAC or 240 VAC, 50/60 Hz. Frequency measuring range: 40‑65 Hz. Trip accuracy: ±0.1 Hz. Time delay accuracy: ±2% of setpoint. Output contact rating: 5 A at 250 VAC resistive. Operating temperature range: ‑20°C to +65°C. The module is housed in a flame‑retardant enclosure suitable for panel mounting.

Operating Principles

The UF 312 continuously measures the input frequency using a digital counting technique. When the measured frequency drops below the adjustable setpoint, the timer starts. If the frequency remains below the setpoint for the entire delay period, the output relay is energized. The trip signal can be used for load shedding, generator tripping, or audible/visual alarms.

Applications

This module is widely used in diesel and gas generator sets, utility substations, and industrial co‑generation plants. It is essential for underfrequency load shedding schemes, where non‑critical loads are disconnected to restore system frequency. It also serves as a backup protection for frequency‑sensitive processes.

Installation and Configuration

Mount the UF 312 on a panel using the provided brackets. Connect the voltage inputs to the bus or generator PT, and wire the output contacts to the control circuit. Adjust the trip setpoint and delay using the front‑panel potentiometers. A calibration check using a precision frequency source is recommended.

Maintenance and Reliability

The solid‑state construction ensures high immunity to vibration and shock. Periodic testing with an external frequency source validates the trip accuracy. The module has no user‑serviceable parts; any malfunction requires replacement. With proper installation, it offers years of trouble‑free operation.

Conclusion

The Basler UF 312 Under Frequency Protective Module provides dependable frequency monitoring and protection. Its adjustable settings and robust design make it a versatile choice for safeguarding power systems against underfrequency events.