The GEC Alsthom MWTU11D1CD0102C is a high-precision static protection relay from the Midos family, specifically designed for directional power sensing and power flow monitoring. The MWTU series is utilized in sophisticated power system protection schemes to detect reverse power conditions, low forward power, or over-power states. This relay is essential for protecting generators from “motoring” (acting as a motor when the prime mover fails) and for managing inter-connector power levels between different utility grids.

Product Technical Description

The MWTU11 is a single-element static relay that processes both current and voltage inputs to calculate the magnitude and direction of real power (Watts). The “D1CD” configuration identifies its specific hardware build, including calibrated input transducers and high-speed logic elements. It uses a phase-angle comparison method to determine power direction, ensuring high sensitivity even under low-power conditions. The relay is housed in a standard Midos size 4 draw-out case, which allows the internal module to be withdrawn for testing or replacement without disturbing the terminal wiring, while automatically shorting the current transformer (CT) circuits.

 

Product Datasheet & Parameters

• Model Number: MWTU11D1CD0102C
• Series: MWTU (Midos Static Power Range)
• Relay Type: Directional Power / Reverse Power Relay
• Rated Current (In): 1A or 5A (Standard CT secondary)
• Rated Voltage (Un): 110V AC (Standard VT secondary)
• Rated Frequency: 50Hz / 60Hz
• Auxiliary Voltage (Vx): 24V – 125V DC (Wide-range supply)
• Setting Range: 0.5% to 20% of rated power (Adjustable for high sensitivity)
• Operating Characteristic: Definite Time Delay (Adjustable)
• Case Size: Midos Size 4 draw-out vertical case
• Output Contacts: 2 Normally Open (NO) and 2 Normally Closed (NC) heavy-duty contacts

 

Country of Origin

This protection relay was manufactured by GEC Alsthom (later Alstom/Areva) in the United Kingdom (Stafford, UK).

 

Application Fields

• Generator Protection: Detecting reverse power to prevent damage to steam or gas turbines (anti-motoring).
• Grid Interconnections: Monitoring power flow directions at tie-points between utility and industrial grids.
• Marine Power Systems: Protecting shipboard generators during parallel operation.
• Industrial Cogeneration: Managing power export/import limits for plants with on-site generation.
• Load Shedding: Providing a directional trigger for automated load management during power imbalances.

 

Product Usage Instructions

When installing the MWTU11, pay strict attention to the polarity of both the CT and VT connections; incorrect phase relationship will result in erroneous power direction readings. The relay should be mounted in a standard 19-inch rack or individual panel cutout. Use the front-panel potentiometers to set the “Pickup” power level and the “Time Delay” to avoid nuisance tripping during transient power swings. During commissioning, perform a directional check by intentionally creating a known power flow and verifying the relay’s response. The draw-out module can be removed safely while the system is live, as the Midos case handles CT shorting automatically.

 

Common Questions & Answers (Q&A)

Q: Can this relay be used for both Export and Import power monitoring? A: The MWTU11 is typically configured for one direction (e.g., Reverse Power). For bidirectional monitoring, two units are often employed or a specialized bidirectional model is selected.

Q: How does this relay protect a turbine? A: If a turbine loses its fuel source, it begins to draw power from the grid to keep spinning (motoring). The MWTU11 detects this reverse power flow and trips the main breaker to prevent mechanical damage to the turbine blades and bearings.

Q: Is the auxiliary DC supply mandatory for operation? A: Yes. As a static (electronic) relay, the MWTU11 requires a stable DC auxiliary supply to power its internal measurement circuits and output relays.

Q: What is the significance of the “Relay Healthy” LED? A: The green LED indicates that the internal power supply is active and the measurement circuitry is operational. If this LED is dark, the relay will not trip even during a power fault.

 

Similar Model Recommendations

1. GEC Alsthom MWTU12 (Three-phase version)
2. GEC Alsthom MWTU13 (Dual-element version)
3. Alstom MiCOM P34x (Modern digital generator protection)
4. GEC Alsthom METI series (Associated time-delay relays)
5. GEC Alsthom GRP series (Generator protection)