Basler UFOV 260A Underfrequency Overvoltage Protective Module – Dual Function Protection
The Basler UFOV 260A (catalog number 9105100-105) is a compact solid-state protective module designed to monitor both frequency and voltage on AC power systems. It provides two independent protection functions: underfrequency (81U) and overvoltage (59), making it ideal for safeguarding generators, motors, and transformers from adverse electrical conditions that could lead to equipment damage or process interruption.
Operating Principle
The module continuously measures the input voltage waveform and derives both the RMS voltage magnitude and the fundamental frequency. When the frequency drops below a preset threshold (underfrequency) or the voltage rises above a preset limit (overvoltage), the module activates its internal output relays to trip circuit breakers or sound alarms. The two functions operate independently with individual setpoints and time delays.
Key Features
Underfrequency trip setting range: 45–60 Hz (adjustable) with time delay 0.1–10 s
Overvoltage trip setting range: 110–150% of nominal voltage (adjustable) with time delay 0.1–10 s
Nominal voltage input: 120 VAC or 240 VAC (selectable)
Output relays: Two Form C (SPDT) contacts, rated 5 A at 250 VAC
Wide auxiliary supply: 24–250 VDC or 100–240 VAC
LED indicators for power, underfrequency trip, and overvoltage trip
Reset pushbutton for manual reset after trip
Accuracy and Response
The UFOV 260A utilizes a digital measurement engine with crystal-controlled time base, ensuring frequency accuracy of ±0.02 Hz and voltage accuracy of ±1% of reading. The response time for underfrequency detection is typically less than 100 ms, while overvoltage detection is less than 50 ms, meeting the requirements of fast-acting protection schemes.
Setting and Configuration
All setpoints are adjusted via front-panel trimpots, each with a calibrated scale for easy reference. The time delays are also adjustable using potentiometers. A test pushbutton is provided to simulate a trip condition for verification of wiring and logic. The module retains its settings even after power loss.
Installation and Wiring
The UFOV 260A is designed for DIN-rail or panel mounting with a compact housing. The rear terminal block is clearly labeled for power supply, voltage sensing input, and relay outputs. The module supports both single-phase and three-phase sensing (using an external phase-to-neutral or phase-to-phase voltage). Proper fusing of the sensing inputs is recommended for protection against short circuits.
Applications
This protective module is widely used in generator control panels, motor control centers, and utility substations. Underfrequency protection prevents generators from overspeeding during load shedding, while overvoltage protection safeguards loads from regulator failures or ferroresonance. It is also applied in cogeneration plants and distributed generation (DG) systems to comply with grid interconnection standards.
Maintenance and Diagnostics
The UFOV 260A is maintenance-free under normal operating conditions. Periodic testing using a variable frequency/voltage source is recommended to confirm setpoint accuracy. The module's self-diagnostic circuit monitors its internal power supply and will indicate a fault via a dedicated LED if an internal failure occurs.
Compliance
This module meets the requirements of IEC 60255 for measuring relays and protection equipment, and carries CE and UL markings. It is designed for harsh environments with an operating temperature range of -20°C to +70°C and is protected against transient overvoltages per IEC 61000-4-5.
Conclusion
The Basler UFOV 260A provides a reliable, cost-effective solution for combined underfrequency and overvoltage protection. Its compact size, ease of setting, and robust construction make it a staple in modern power protection schemes.
