12SGC21B4A GE

Description

Product Name : 12SGC21B4A GE Input module

Product details:

The GE 12SGC21B4A is a specialized Type SGC Static Negative Phase Sequence Time Overcurrent Relay manufactured by General Electric.

It is designed to protect medium and large electrical equipment—such as generators, synchronous motors, and high-voltage transmission equipment—against unbalance phase currents, single-phasing, or phase-to-phase faults by monitoring the negative sequence current (I_2).

Key Technical Specifications

• Model/MPN: 12SGC21B4A (Revision B)
• Relay Type: Static / Solid-State Negative Sequence Time Overcurrent Relay
• Rated AC Current (I_n): 5 Amperes
• Rated Frequency: 60 Hz
• Auxiliary DC Power Voltage: 125 VDC / 250 VDC
• One Per Unit (1.0 p.u.) Range: Adjustable from 3.1 A to 4.9 A
• Meter Output Signal: 2.5 VDC corresponds to 1.0 Per Unit (p.u.)
• Associated Sub-assembly: Includes Pre-Regulator Board (e.g., 138B7511 G2)
• Physical Mounting: Panel-mounted / Switchgear Drawout Case

Key Product Advantages

• High Sensitivity to Phase Unbalance: Detects minor negative-sequence current increases before severe thermal damage occurs to generator rotors or motor windings.
• Solid-State Reliability: Being a static relay, it offers faster response times, higher accuracy, and reduced mechanical wear compared to older electromechanical equivalents.
• Precise Inverse Time Characteristics: Provides inverse time-delay tripping, allowing temporary unbalanced transients without nuisance tripping while offering fast trip action during heavy faults.
• Built-in Diagnostic Output: Features analog voltage outputs (e.g., 2.5 VDC = 1 p.u.) for easy local metering, calibration, and routine test verification.

Important Precautions & Operating Notes

1. Power Isolation: Ensure the 125V/250V DC auxiliary power supply and CT secondary circuits are completely isolated/shorted before removal or servicing to prevent high-voltage hazards and electric shocks.
2. Current Transformer (CT) Shorting: Always short-circuit the CT secondary terminals before drawing out or disconnecting the relay module to avoid lethal open-circuit voltages.
3. DC Control Voltage Verification: Confirm that the DC control bus voltage matches the rating (125 VDC or 250 VDC) prior to powering up the pre-regulator circuit.
4. Periodic Testing & Calibration: Calibration should be checked using dedicated relay test sets to verify pickup thresholds (I_2) and time-dial characteristics according to original GE manufacturer curves.
5. Static/ESD Handling: Handle internal cards with proper Anti-Static/ESD precautions to avoid damaging sensitive semiconductor components.

Primary Applications

• Generator Protection: Safeguards utility and industrial generators against severe heating caused by asymmetrical loads or phase loss.
• Large Synchronous & Induction Motors: Prevents rotor overheating resulting from phase imbalance or utility single-phasing conditions.
• Substation Switchgear Integration: Integrated into high-voltage protection schemes alongside distance or differential relays to form a comprehensive protection matrix.

Advantages: Foxboro, OVATION, TRICONEX, Allen-Bradley, ABB, Motorola, Siemens Moore, Ge Fanuc, Woodward, Bently Nevada and other major import brands!

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Colour：new Warranty: 12 months
Lead Time：3-day working day Country of origin: United States
Price: Please contact us Product weight：0.515kg
Shipping Port: Xiamen, China
Payment: Bank of Chicago, Bank of Singapore
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