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1. Introduction
The Thytronic SVF5940#U3F3 is an interface protection relay designed to monitor and protect low‑ and mid‑voltage electrical networks. It continuously measures voltage and frequency parameters and triggers protective actions if values exceed configurable thresholds. This device is commonly used for grid‑interconnected protection and network stability applications.
2. Safety Precautions
✔ Installation and configuration should be performed by qualified personnel.
✔ Disconnect all power before wiring or servicing the relay.
✔ Ensure the protective relay is rated for 400 V networks and correct supply voltage.
✔ Do not expose the device to moisture, dust, or direct sunlight.
3. Functional Overview
The SVF5940 monitors the electrical network and provides the following core functions:
Voltage Protection:
• Undervoltage trip (protects against voltage drop)
• Overvoltage trip (protects against excessive voltage)
Frequency Protection:
• Underfrequency trip (detects too slow frequency)
• Overfrequency trip (detects too fast frequency)
Rate of Change of Frequency:
• 81R protection against rapid frequency changes
(This type of functionality is typical for SVF5940 relays.)
4. Power Supply
Connect the auxiliary power to the appropriate terminals according to the device specification. This relay typically requires a stable power supply compatible with its voltage rating (often auxiliary supply in the range specified on the product label).
5. Wiring Connections
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Voltage Sensing Inputs: Connect line voltage inputs for measurement.
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Frequency Measuring Inputs: Frequency is derived from voltage inputs.
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Protection Output Relays: Connect the relay outputs to the grid‑disconnect contactor or circuit breaker.
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Auxiliary Power: Connect the device’s auxiliary supply to the correct terminals.
Always follow the wiring diagram on the device label or manufacturer datasheet.
6. Setting Protection Thresholds
Protection settings determine at what measured values the relay will trip. Common threshold adjustments include:
✔ Minimum voltage trip level
✔ Maximum voltage trip level
✔ Underfrequency level
✔ Overfrequency level
✔ Time delay settings before trip
Settings are typically adjusted via dedicated configuration buttons, DIP switches, or software, depending on the relay variant.
7. Indicators and Diagnostics
Most interface protection relays include LED indicators or display readouts showing:
• Power ON
• Normal operation (no fault)
• Fault condition
• Output relay activation
These help diagnose network conditions and confirm proper relay operation.
8. Normal Operation
Once powered and configured, the relay continuously monitors network voltage and frequency. If any parameter goes outside set thresholds:
✔ The relay triggers
✔ Output relays switch to open the grid disconnect device
✔ The network generator or other equipment is safely disconnected
Refer to the product label or technical datasheet for specific trip logic and output behavior.
9. Maintenance
✔ Periodically inspect all wiring connections and terminal tightness.
✔ Verify correct operation of threshold settings during system commissioning.
✔ Test protective functions under controlled conditions at regular intervals.
10. Compliance and Standards
Devices of this type are typically certified for protective operation according to applicable network standards such as ENEL/CEI interface protection requirements.
11. Troubleshooting
If the relay fails to operate correctly:
✔ Check the auxiliary power supply voltage.
✔ Confirm proper connection of voltage and frequency inputs.
✔ Ensure the threshold settings are correctly configured.
✔ Inspect relay outputs and wiring to control devices.
