Description
Product Core Brief
- Model: SPAD346C
- Brand: ABB
- Series: ABB SPACOM protection relay family
- Core Function: Stabilized three-phase differential relay with integrated overcurrent and earth-fault protection for power transformers and generator-transformer units.
- Product Type: Integrated protection relay
- Key Specs: Differential protection | Overcurrent backup | Earth-fault protection | CT ratio correction | Harmonic restraint | Disturbance recorder
- Condition: New Original (New Surplus) / Factory Sealed
Product Introduction
When a transformer differential relay fails or a spare unit is required for planned maintenance, the protection scheme loses its primary defense against winding faults. The ABB SPAD346C is an integrated stabilized differential relay designed to protect two-winding power transformers and generator-transformer units against winding short-circuits, interturn faults, earth faults, and short circuits.
This relay is no longer an active ABB product, having been discontinued since 2012, so it is typically sourced as a replacement for legacy installations, retrofit projects, or critical spare stocking. Before ordering, confirm the exact sub-model on the nameplate, since SPAD346C and SPAD346C3 may differ in module configuration or application scope.
Key Technical Specifications
- Part Designation:
- Brand: ABB
- Application: Two-winding power transformers, generator-transformer units, and selected three-winding transformer applications
- Module Type: Integrated protection relay
- Protection Functions: Stabilized three-phase differential protection, overcurrent protection, earth-fault protection
- CT Compatibility: 1A and 5A rated current inputs; high-side and low-side may use the same or different rated currents
- Differential Features: Second-harmonic restraint for inrush blocking, fifth-harmonic restraint for overexcitation, CT ratio correction, and vector-group matching for two-winding transformers
- Earth-Fault Options: Stabilized differential current principle, high-impedance principle, residual overcurrent, or neutral-point overcurrent
- I/O: Four trip and four signal relay outputs; five programmable external control inputs
- Disturbance Recorder: Integrated recorder for current and digital signals
- Operating Temperature: -10…+55 °C
- Enclosure Rating: IP54 for the embedded relay housing
- Product Status: Not active product since 2012
- Condition: New Original (New Surplus) / Factory Sealed
- Note: Exact hardware revision, module configuration, and communication options should be verified against the nameplate and ABB documentation.
Key Selling Points & Differentiators
- Exact legacy replacement: Supplied as SPAD346C to support like-for-like replacement in existing transformer protection bays.
- Integrated protection functions: Combines differential, overcurrent, and earth-fault protection in one relay unit.
- Transformer-ready features: Supports CT ratio correction, harmonic restraint, and vector-group matching without requiring intermediate CTs for two-winding transformers.
- Disturbance recording included: Helps with post-fault analysis and commissioning verification.
- Factory-sealed supply: Shipped with ESD-safe handling and visual QA before dispatch.
- Not recommended for new greenfield projects where modern ABB Relion or REF/RET/REM series relays are specified, or for applications requiring active OEM support and current firmware updates.
Quality Transparency SOP
- Visual inspection: Check front panel, display, connectors, mounting hardware, and labeling for damage or corrosion.
- ESD-safe handling: Packed in anti-static protection to prevent damage to internal electronics.
- Connector verification: Inspect CT inputs, binary I/O terminals, communication ports, and power supply terminals.
- Nameplate cross-check: Confirm SPAD346C designation, sub-model, and hardware revision before shipment.
- Functional validation: When compatible test equipment is available, verify power-up response, protection element pickup, LED/status indication, and I/O operation. Full validation depends on the host protection scheme and CT configuration.
Technical Risk Avoidance
❗ Confirm the exact sub-model. SPAD346C and SPAD346C3 are not automatically interchangeable without verifying module configuration and application requirements.
❗ Verify CT secondary current. The relay supports 1A and 5A CT inputs; mismatched CT ratings can cause incorrect differential measurement.
❗ Check vector-group and CT ratio settings. Incorrect transformer vector-group or CT ratio parameters may cause false differential currents.
❗ Follow secondary injection testing. Replacement relays should be tested with secondary injection before being placed into service.
❗ Confirm product lifecycle status. SPAD346C is a legacy product; long-term support, firmware updates, and spare availability should be evaluated for critical installations.
Buyer’s FAQ
Is this an original ABB part?
Yes. The listing is for ABB SPAD346C as a new original/new surplus, factory-sealed unit. We do not relabel third-party substitutes.
Which application does SPAD346C fit?
It is designed for two-winding power transformers and generator-transformer units, with integrated differential, overcurrent, and earth-fault protection.
Can replace SPAD346C3?
Not automatically. They belong to the same relay family but may differ in module configuration and application scope. Confirm the existing nameplate and protection scheme before substitution.
What condition is the unit?
New Original (New Surplus) / Factory Sealed, unless otherwise stated in the product listing. Photos and batch details can be confirmed before dispatch.
Do you offer a warranty?
Yes. A standard warranty applies from receipt. Exact terms depend on stock batch and installation conditions. Installation and testing should be performed by qualified protection and control engineers.
