Product Core Brief
- Model: SAFT183VMC
- Brand: ABB Hitachi Energy
- Series: SAFT series medium voltage fuse mounting hardware for indoor air-insulated switchgear
- Core Function: Single-pole vertical mount fuse base designed for 12kV medium voltage current-limiting fuses, installed inside ABB UniGear ZS3.2, ZS3.3 and SafeRing switchgear transformer feeder bays. It provides mechanical support, reliable high-current conductive contact and fault trip linkage for MV fuses. When the fuse blows due to short-circuit or overload, the integrated mechanical striker releases a trip signal to open the upstream circuit breaker, preventing transformer permanent damage. The VMC suffix stands for Vertical Mount, complete with built-in micro-switch fault signal output and anti-corrosion conformal coating for humid industrial environments.
- Product Type: Medium Voltage Vertical Mount Fuse Holder Base Assembly
- Key Specs: Rated voltage 12 kV; rated continuous current up to 630 A; vertical cabinet installation orientation; integrated striker tripping microswitch; silver-plated contact jaws; epoxy insulated housing; compatible with ABB CMF series MV current-limiting fuses; 24V DC/AC fault alarm contact output
- Note: Still active OEM production for new MV switchgear projects and legacy power plant transformer bay maintenance; factory-sealed original assemblies and fully bench-tested surplus units are widely supplied for urban distribution substations, chemical plants, water treatment stations and industrial self-generation power plants.
Key Technical Specifications
| Parameter | Value |
|---|---|
| Full Model Code | |
| Nominal System Voltage | 12 kV (10 / 12 kV class indoor application) |
| Rated Continuous Current | Up to 630 A matching standard CMF fuse sizes |
| Mounting Type | Vertical panel mounting inside switchgear compartment |
| Fault Trip Mechanism | Built-in striker pin + auxiliary microswitch; contact closes when fuse operates |
| Auxiliary Signal Contacts | 1 set of isolated changeover Form-C contacts, rated 250 VAC/DC, 5 A max for DCS/SCADA fault signaling |
| Main Contact Material | Silver-plated copper jaws to minimize contact resistance and overheating |
| Insulation Housing Material | High-strength flame retardant epoxy resin, arc resistant |
| Conformal Coating | ISA G3 anti-salt, anti-moisture coating for corrosive indoor workshops |
| Mechanical Operation Life | Minimum 100 fuse replacement cycles without contact degradation |
| Operating Ambient Temperature | -10 °C ~ +55 °C inside sealed switchgear compartment; storage -40 °C ~ +70 °C |
| Humidity Class | ≤ 95% RH non-condensing |
| Overall Dimensions | 285 mm H × 130 mm W × 142 mm D |
| Net Weight | Approx. 4.8 kg |
| Compliance Standards | IEC 60282-1 high voltage fuse standard, IEC 62271-200 switchgear standard, KEMA type-tested, CE certified |
Product Introduction
The is a vertical-install MV fuse base specially developed for ABB indoor air-insulated medium voltage switchgear, serving as the mechanical and electrical carrier for transformer protection current-limiting fuses. It solves three core functional demands of MV transformer bays:
- Reliable High-Current Conductive ConnectionSilver-plated multi-contact jaw structure provides uniform clamping force on the fuse tube body, greatly reducing contact resistance during long-term full-load operation and avoiding thermal overheating and fuse premature burnout. The epoxy insulating housing fully isolates live high-voltage parts to eliminate accidental electric shock risks during routine inspection.
- Automatic Fault Trip Interlock FunctionEach integrates a built-in striker microswitch linkage system. When the internal fuse melts under overload or short-circuit fault, the spring-driven striker pin pops out and triggers the auxiliary switch, immediately sending a fault alarm signal to the substation SCADA system and outputting trip logic to open the upstream circuit breaker to isolate the faulty transformer branch. This avoids long-duration transformer winding fault damage caused by delayed isolation.
- Vertical Layout Space OptimizationThe vertical mounting design matches the internal compartment layout of ABB UniGear series switchgear, saving horizontal cabinet space and facilitating single-phase fuse replacement maintenance without removing adjacent three-phase components. The conformal coating treatment adapts to high-humidity industrial workshops and coastal distribution stations with mild salt fog corrosion.
It must be matched with ABB CMF series 12kV current-limiting fuses of corresponding rated current, and cannot be used with low-voltage distribution fuses or horizontal mount SAFT series variants such as SAFT183HMC due to different mechanical dimensions and tripping linkage structures.
QA & Testing SOP (Transparency Building)
- Incoming Visual Inspection: Verify full model against ABB switchgear spare parts database to reject mismatched horizontal mount bases; inspect epoxy housing, silver contact jaws, striker pin mechanism and conformal coating for cracks, discoloration or scratch damage; record serial numbers and production batches for full traceability.
- Full Mechanical Linkage Test: Install matched CMF fuse into base on standard switchgear test bench; simulate fuse blowout striker ejection to verify microswitch reliable trigger and stable contact continuity; run 24-hour cyclic mechanical test of fuse insertion and fault tripping without jamming.
- Contact Resistance & Insulation Test: Measure main jaw contact resistance ≤ 80 μΩ under rated clamping force; insulation resistance tester confirms ≥ 10 MΩ between high-voltage main circuit and low-voltage signal microswitch terminals; chassis ground continuity resistance below 0.5 Ω.
- Hardware Record Backup: Photograph vertical mounting hole positions, microswitch signal terminal wiring definitions and fuse installation sequence for field maintenance reference.
- Final QC Packaging: Wipe epoxy housing surface with anti-static microfiber cloth, cover all high-voltage contact jaws and signal terminal blocks with insulating protective caps, place the assembly into shockproof foam carton with independent ESD inner bag, attach unified printed QC test tag with technician ID and full 24-hour linkage test runtime timestamp.
Installation Pitfalls & 4-Step Replacement Guide
Common Installation Hazards
❗ High-Voltage Residual Charge Hazard: Execute full lockout/tagout of MV switchgear primary circuit, wait minimum 15 minutes for VT/CT residual charge release before disassembling the base to avoid electric shock.❗ Vertical/Horizontal Model Mismatch Risk: is vertical mount only; replacing with horizontal SAFT183HMC will cause fuse misalignment, poor contact and tripping linkage failure.❗ Insufficient Fuse Jaw Clamping Torque: Under-tightened fuse clamping bolts lead to high contact resistance and local overheating during heavy load operation; follow ABB specified torque values strictly.❗ Striker Pin Mechanical Blockage: Do not install foreign plastic insulation barriers between fuse striker and microswitch; blocked pins disable fault trip interlock and create blind protection zone.❗ ESD Microswitch Damage Risk: Wear certified anti-static wrist strap during all disassembly and installation work; bare hand contact with internal signal PCB traces will damage fault alarm trigger circuits.
4-Step Base Assembly Replacement Guide
- Pre-install Preparation: Lock out and tag out the 12kV primary circuit of the transformer bay, wait 15+ minutes for complete residual charge discharge, wear ESD wrist strap, photograph vertical mounting bolt positions, fuse jaw clamping structure and microswitch fault signal wiring on inside the switchgear compartment.
- Removal Operation: Extract the CMF fuse tube from the old base first; loosen vertical panel mounting bolts, disconnect the microswitch alarm signal terminal wires one by one, remove the entire fuse base assembly from cabinet compartment.
- Installation & Wiring: Fix the new vertically onto the original panel mounting frame with standard torque bolts; re-terminate the microswitch fault alarm signal wiring strictly following photographed sequence, insert the matched CMF fuse tube and tighten jaw clamping bolts to standard torque, confirm striker pin can eject freely without obstruction.
- Power-on Commissioning Test: Restore auxiliary control power for the microswitch signal circuit, manually push the striker pin to simulate fuse fault, verify auxiliary switch closes and fault signal uploads normally to DCS/SCADA; close MV primary power, run transformer no-load operation for 1 hour, check no abnormal overheating alarm on the switchgear diagnostic system.
FAQ
Q: What is the difference between and SAFT183HMC?
- : Vertical mounting structure, this model, used for standard vertical compartment layout UniGear switchgear;
- SAFT183HMC: Horizontal mounting variant, for horizontal fuse compartment designs, different mechanical dimensions and striker linkage positions, cannot interchange.
Q: Can work without the striker microswitch signal output?It can mechanically hold the fuse alone, but the fault trip interlock function will be lost. The microswitch contact signal is mandatory for transformer bay protection coordination to stop the transformer when fuse failure occurs.
Q: Can the base be hot-swapped with MV primary circuit energized?Absolutely prohibited. The base is connected to live 12kV medium voltage circuits; disassembly under energized conditions will trigger severe arc flash accidents and fatal electric shock. Full primary power lockout and residual charge discharge are mandatory before replacement.
Q: What warranty applies to stocked assemblies?Factory-new original fuse bases carry 12-month official ABB manufacturer warranty covering silver contact jaws, striker mechanical linkage, epoxy insulation housing and microswitch signal contacts. Bench-tested surplus assemblies provide 6-month functional warranty; damage caused by loose contact overheating, striker pin blockage or ungrounded ESD handling voids all warranty terms.
Q: Has ABB discontinued production?No formal EOL notice issued; remains standard supply for new UniGear MV switchgear projects. It is the dedicated vertical fuse base for transformer feeder bays and cannot be replaced by other SAFT series horizontal mount models.
Q: What typical faults indicate a defective base?Common failure symptoms: Persistent transformer overheating alarm without fuse burnout, failure to send fault signal to SCADA after fuse blows, loose fuse tube causing random contact loss and intermittent transformer tripping, striker pin jamming unable to eject during fault conditions, visible contact jaw discoloration and overheating marks under normal load operation.
