ALSTOM MMLG01 Standard Test Block | Replacement, Equivalent & Selection Guide
The ALSTOM MMLG01 is a standard test block designed for use with protection relay systems, enabling safe in-service testing, commissioning, and maintenance of relay circuits without interrupting primary current or voltage circuits. This page provides full technical specifications, compatible replacement models, application guidance, and a structured selection guide to help engineers and procurement teams make informed decisions.
Technical Specifications
| Manufacturer | ALSTOM (now GE Grid Solutions / GE Vernova) |
| Model | MMLG01 |
| Type | Standard Test Block (Plug-in Test Block) |
| Function | Isolates relay from CT/VT circuits for safe testing |
| Rated Current | Up to 10 A (CT secondary) |
| Rated Voltage | Up to 250 V AC/DC |
| Contact Configuration | Multi-pole shorting/isolating contacts |
| Mounting | Panel / DIN rail compatible |
| Insulation Class | IEC 60255 compliant |
| Operating Temperature | -10°C to +55°C |
| Weight | Approx. 100 g |
| SKU | MMLG01 |
Compatible Replacement & Equivalent Models
The following models are commonly evaluated as replacements or equivalents for the ALSTOM MMLG01. Always verify electrical ratings, pole configuration, and mechanical dimensions before substitution.
| Model | Manufacturer | Compatibility Notes |
|---|---|---|
| MMLG01 | GE Grid Solutions (successor) | Direct OEM continuation — preferred replacement |
| MMLG011 | ALSTOM / GE | Extended pole variant; verify pole count requirement |
| MMLG021 | ALSTOM / GE | Higher current rating variant; check CT secondary rating |
| MMLB01 | ALSTOM / GE | Blocking test plug companion; used with MMLG series |
| MMLG31 | ALSTOM / GE | Alternative configuration; confirm terminal layout |
| RTB (Generic) | Various (Omicron, Megger) | Universal test blocks — verify pin-out compatibility |
Note: Third-party equivalents may require adapter harnesses. Consult your relay OEM documentation before substitution.
Why Choose the Original MMLG01
- OEM-certified compatibility — designed and validated specifically for ALSTOM/GE MMLG-series protection relays
- Zero-interruption testing — shorting contacts safely isolate CT circuits, preventing open-circuit hazards during live testing
- Proven field reliability — widely deployed in substations, power plants, and industrial protection panels globally
- Long service life — robust contact materials rated for repeated insertion/withdrawal cycles
- Protection relay commissioning and periodic maintenance testing
- Current transformer (CT) and voltage transformer (VT) circuit isolation
- Substation automation and SCADA-integrated protection panels
- Industrial motor protection and feeder protection schemes
- Generator and transformer differential protection systems
- Distance protection relay testing (e.g., ALSTOM LFZP, MICOM P series)
- ALSTOM LFZP series (distance protection)
- ALSTOM MCGG / MCAG series (overcurrent protection)
- ALSTOM MVAX / MVAJ series (auxiliary relays)
- GE MiCOM P100 / P200 / P300 / P400 / P500 series
- GE MiCOM Agile P series (newer generation)
- ALSTOM KBCH / KCGG series (legacy electromechanical relays)
- Authentic OEM stock — Konmask.com sources MMLG01 units from authorized distributors and verified industrial surplus channels
- Pre-shipment inspection — each unit is visually inspected and contact-continuity verified before dispatch
- Traceability — batch records and supplier documentation available upon request for critical infrastructure projects
- Anti-counterfeit policy — we do not stock or sell counterfeit or uncertified components
- Warranty — 12-month warranty against manufacturing defects; DOA replacement within 30 days
- Confirm your relay model and required test block variant (MMLG01 / MMLG011 / MMLG021)
- Add the ALSTOM MMLG01 to your cart or contact us for bulk/project pricing
- Provide your project PO number and delivery address at checkout
- For urgent requirements, email support@konmask.com with your timeline
- International orders: DDP/DAP shipping available — contact us for customs documentation support
Typical Applications
System Compatibility
The MMLG01 test block is compatible with the following ALSTOM / GE relay families (non-exhaustive):
For other relay families, confirm the test block terminal layout against the relay’s wiring diagram before installation.
Selection Guide
Use the following criteria to select the correct test block for your application:
| Selection Criterion | Guidance |
|---|---|
| Relay model | Match test block to relay’s designated MMLG variant per relay manual |
| Pole count | Count CT/VT and binary I/O circuits requiring isolation; select MMLG01 / MMLG011 / MMLG021 accordingly |
| CT secondary rating | Confirm 1 A or 5 A CT secondary; verify test block current rating matches |
| Voltage rating | Ensure test block rated voltage ≥ VT secondary voltage (typically 110 V or 63.5 V) |
| Mounting space | Verify panel cutout dimensions; MMLG01 requires standard ALSTOM panel mounting |
| Replacement vs. new installation | For like-for-like replacement, use OEM MMLG01; for new panels, consider current GE MiCOM test block equivalents |
Quality Assurance & Sourcing
How to Order
Replacement & Compatibility FAQ
Q: Can I use a generic RTB (relay test block) instead of the MMLG01?
A: Generic test blocks may be physically compatible but could differ in contact shorting sequence and current rating. Always verify against the relay’s wiring diagram. For critical protection applications, OEM parts are strongly recommended.
Q: Is the MMLG01 still manufactured?
A: ALSTOM’s grid protection division was acquired by GE (now GE Vernova). The MMLG01 continues to be available as a GE Grid Solutions part. Konmask.com also maintains stock of genuine legacy ALSTOM units.
Q: What is the difference between MMLG01 and MMLG011?
A: The MMLG011 typically offers an additional pole configuration for more complex relay wiring schemes. Refer to your relay’s installation manual for the correct variant designation.
Q: Can the MMLG01 be used with MiCOM P series relays?
A: Yes, the MMLG01 is compatible with many MiCOM P series relays. Confirm the specific relay model’s test block requirement in the GE MiCOM relay manual.
Q: Do you offer project/bulk pricing?
A: Yes. Contact support@konmask.com with your BOM and required quantities for a project quotation.
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