Description
Product Core Brief
- Model: SPAD 346 C — ABB stabilized differential relay
- Brand: ABB
- Series: ABB SPA-series legacy protection relays
- Core Function: Integrated three-phase stabilized differential relay with overcurrent and earth-fault protection for two-winding power transformers and generator-transformer units.
- Product Type: Transformer differential protection relay
- Key Specs: Three-phase differential protection | Overcurrent backup | Earth-fault protection | CBFP | Disturbance recorder | 1 A / 5 A CT input
- Condition: New Original (New Surplus) / Factory Sealed — when available
Product Introduction
The ABB SPAD 346 C is a legacy stabilized differential relay designed for protecting two-winding power transformers and generator-transformer arrangements against winding short-circuits, interturn faults, earth faults, and short circuits. It integrates three protection modules: a three-phase stabilized differential module SPCD 3D53, an earth-fault module SPCD 2D55, and an overcurrent/earth-fault combination module SPCJ 4D28.
Because this relay has been listed as a not-active product since 2012, verified surplus units are often used to support legacy transformer bays, retrofit replacements, and maintenance spares where the original protection scheme must be preserved.
Key Technical Specifications
- Part Designation: SPAD 346 C — ABB stabilized differential relay
- Product Type: Integrated transformer differential protection relay
- Application: Two-winding power transformers, generator-transformer units; three-winding transformers when 75% of short-circuit power is supplied from the same direction
- Differential Protection: Stabilized three-phase differential protection with harmonic restraint
- Overcurrent Protection: Three-stage overcurrent protection
- Earth-Fault Protection: High-impedance, residual overcurrent, neutral overcurrent, or stabilized differential earth-fault principles
- CBFP: Circuit-breaker failure protection with adjustable operating time
- Disturbance Recorder: Integrated fault recorder for currents and digital signals
- CT Rated Current: 1 A and 5 A
- Outputs: Multiple trip and signal relay outputs; programmable external control inputs
- Replacement Type: Obsolete / surplus replacement component
- Packaging: ESD-protected, shock-aware industrial packing
- Traceability: Label, revision, and type marking verification required before installation
- Supply Status: New Original / New Surplus inventory, subject to availability
- Warranty: 12 months from shipment
- Lead Time: Dispatch depends on current surplus stock
- Note: Exact configuration depends on the transformer, CT ratios, vector group, and protection scheme
Key Selling Points & Differentiators
- Legacy ABB differential relay for transformer bays that still use SPA-series protection.
- Integrated differential, overcurrent, and earth-fault functions in one relay assembly.
- Supports harmonic restraint to avoid tripping on transformer inrush or overexcitation.
- Suitable for replacement, maintenance spares, and legacy system support.
- Factory-sealed surplus reduces handling risk compared with used pulls.
- Not recommended for new designs unless the existing protection scheme requires it.
Quality Transparency SOP
- Visual inspection: Check housing, front panel, terminal blocks, labels, and SPAD 346 C marking.
- Module verification: Confirm presence of SPCD 3D53, SPCD 2D55, and SPCJ 4D28 modules where applicable.
- Connector verification: Confirm CT input terminals, trip outputs, and control input integrity.
- Setting review: Match CT ratios, vector group, differential slope, and earth-fault principle to the existing scheme.
- Documentation review: Confirm part number, revision, lot/serial traceability, and packing condition.
Technical Risk Avoidance
- ❗ Confirm the exact relay type before ordering. SPAD 346 C is a transformer differential relay, not a feeder overcurrent relay.
- ❗ Verify the required CT rated current. The relay supports 1 A and 5 A CT inputs.
- ❗ Check module configuration. The relay is built from plug-in modules, and missing or mismatched modules can prevent correct operation.
- ❗ Do not assume direct interchangeability with other SPA relays or modern numerical relays without engineering review.
- ❗ De-energize and follow proper lockout/tagout before removing or installing relay modules.
- ❗ After replacement, differential protection settings, CT polarity, and trip circuits must be verified by qualified protection engineers.
Buyer’s FAQ
- Is this a genuine ABB part?
It is supplied as an ABB SPAD 346 C stabilized differential relay. Traceability should be confirmed through labeling and packaging before installation. - Is it new or refurbished?
Listed as New Original / New Surplus, factory sealed when available. It is not a repaired or refurbished relay. - What does SPAD 346 C protect?
It protects two-winding power transformers and generator-transformer units against winding short-circuits, interturn faults, earth faults, and short circuits. - Is SPAD 346 C still in production?
No. It has been listed as a not-active product since 2012. - Can it protect three-winding transformers?
It can be used for three-winding transformers only when 75% of the short-circuit power is supplied from the same direction. - What warranty and lead time apply?
Standard 12-month warranty from shipment. Lead time depends on current surplus inventory and module availability.
