MRJ Series Twin-Bundle Conductor Spacer for Flexible Busbars
The MRJ series twin-bundle conductor spacer is a mechanical power fitting used to maintain a controlled distance between two parallel subconductors. It is commonly installed in twin-bundle flexible busbar systems, substation conductor assemblies and compatible overhead-line applications.
The spacer consists of a rigid metal body with two conductor-clamping ends. Each end surrounds and secures one conductor through a bolted keeper or cover. After installation, the fitting helps maintain the designed bundle geometry and reduces the possibility of conductor contact, entanglement or excessive relative displacement.
The clamp body and keeper are generally manufactured from aluminum alloy to provide low weight, corrosion resistance and compatibility with aluminum-based conductors. Bolts, nuts and washers may be supplied in hot-dip galvanized steel or stainless steel according to the environmental and project requirements.
Important: The product shown has a rigid metal structure and no clearly visible elastomer damping elements. It should therefore be described as a twin-bundle conductor spacer rather than a spacer damper unless damping performance is confirmed by the approved design and test report.
Key Features
- Designed for two parallel subconductors
- Maintains the specified twin-bundle conductor spacing
- Rigid metal body with two bolted clamping sections
- Compact construction for flexible-bus and conductor assemblies
- Aluminum-alloy body available for low weight and corrosion resistance
- Smooth conductor-contact surfaces help reduce localized conductor damage
- Replaceable bolts, nuts, washers and clamping components
- Different conductor diameters and spacing dimensions available
- Custom dimensions, materials and hardware configurations available
Typical Technical Specifications
| Product Type | Twin-Bundle Conductor Spacer |
|---|---|
| Series | MRJ Series |
| Bundle Configuration | Twin bundle / two subconductors |
| Structure | Rigid body with two bolted conductor clamps |
| Body Material | Aluminum alloy, subject to model confirmation |
| Keeper Material | Aluminum alloy, subject to model confirmation |
| Fastener Material | Hot-dip galvanized steel or stainless steel |
| Suitable Conductor | AAC, AAAC, ACSR or project-specified flexible bus conductor |
| Conductor Diameter | Selected according to the exact MRJ model and conductor outside diameter |
| Bundle Spacing | Project-specific; commonly represented by the spacing value in the model designation |
| Installation Method | Bolted mechanical clamping |
| Application | Substation flexible busbar and compatible twin-bundle conductor systems |
| Customization | Conductor range, bundle spacing, body dimensions, bolt material and packaging |
All dimensions and conductor ranges must be checked against the approved product drawing. The photograph alone cannot identify the exact MRJ model.
Product Function
A twin-bundle conductor system uses two parallel subconductors for one electrical phase or busbar section. Without appropriate spacing hardware, the conductors may move toward each other because of wind, electromagnetic force, installation deviation or short-circuit loading.
The MRJ spacer holds both subconductors at a predetermined distance. Correct spacing helps preserve the designed electrical clearance and mechanical arrangement of the busbar or conductor bundle.
Rigid Spacer and Spacer Damper Difference
A rigid conductor spacer primarily maintains the physical distance between subconductors. A spacer damper also incorporates a designed flexible or damping system to control aeolian vibration and subspan oscillation.
The product shown in the photograph has a rigid metal body without visible rubber hinges or elastomer damping elements. It must not be promoted as providing verified vibration-damping performance unless the exact model has passed the required mechanical and damping tests.
Materials and Construction
Aluminum-Alloy Body
The main body and conductor keepers are commonly manufactured from cast aluminum alloy. The material provides a favorable strength-to-weight ratio and is suitable for use with aluminum-based conductors when the correct alloy and contact design are selected.
Steel Fasteners
Bolts, nuts and washers may be manufactured from galvanized carbon steel. Stainless-steel hardware can also be specified for selected environments. The fastener grade, coating and tightening torque must be confirmed for the exact model.
Conductor Contact Area
The conductor grooves should match the outside diameter of the selected conductor. Contact surfaces should be smooth and free from sharp edges, casting flash or projections that could damage individual conductor strands.
Typical Model Selection
MRJ model designations may include information relating to conductor size and bundle spacing. Representative market configurations include spacers for conductor-diameter groups of approximately 19–21 mm, 24–27 mm and 30–33 mm, with nominal spacing options such as 120, 200 or 400 mm.
These values are general selection references and must not be treated as confirmed JIUJIN POWER stock specifications. Final selection must be based on the conductor outside diameter, required center-to-center spacing and approved drawing.
Applications
- Substation twin-bundle flexible busbars
- Power-plant flexible conductor assemblies
- Switchyard conductor connections
- Transformer and switchgear flexible-bus connections
- Twin-bundle overhead conductors where the approved design permits
- Power-system expansion and maintenance projects
Selection Guidance
The following information should be checked before selecting an MRJ spacer:
- Conductor material and construction
- Exact conductor outside diameter
- Number of subconductors
- Required center-to-center bundle spacing
- Continuous operating temperature
- Expected mechanical and short-circuit forces
- Environmental corrosion category
- Required fastener material and coating
- Applicable utility or project standard
Installation Guidance
- Confirm that the spacer model matches the conductor outside diameter and required bundle spacing.
- Inspect the body, keepers, bolts and conductor grooves for damage or contamination.
- Position the two conductors according to the approved center-to-center spacing.
- Place each conductor correctly inside its corresponding clamp groove.
- Install the keepers and all specified washers and fasteners.
- Tighten the bolts evenly using the manufacturer’s specified sequence and torque.
- Confirm that the conductor is securely retained without crushed, cut or displaced strands.
- Verify the final spacer position and conductor spacing after installation.
Installation must be performed by qualified personnel. Improvised bolt torque, incorrect conductor grooves or missing washers may reduce the mechanical reliability of the assembly.
Quality Inspection
- Aluminum-alloy material verification
- Body and keeper dimensional inspection
- Conductor-groove diameter inspection
- Bundle-spacing dimensional inspection
- Casting-surface and internal-defect inspection
- Bolt, nut and washer inspection
- Zinc-coating inspection for galvanized steel components
- Assembly and tightening inspection
- Slip-strength or mechanical-load testing when specified
- Corona and radio-interference testing when required by the application
Reference Standards
- IEC 61854:2020 – Overhead lines: requirements and tests for spacers
- IEC 61284:1997 – Requirements and tests for overhead-line fittings
- ISO 1461:2022 – Hot-dip galvanized coatings on fabricated iron and steel articles
- Applicable utility specifications and approved project drawings
IEC 61854 covers rigid spacers, flexible spacers and spacer dampers for conductor bundles on overhead lines. For a product used specifically in a substation flexible-bus system, the applicable technical requirements must be defined by the project specification.
Reference to a standard does not constitute certification. Compliance statements must be supported by inspection or test documents for the exact product model.
Ordering Information
Please provide the following information when requesting a quotation:
- Required MRJ model or approved drawing
- Conductor type and outside diameter
- Required twin-bundle center spacing
- Body and keeper material
- Fastener material and corrosion-protection requirement
- Required mechanical performance
- Installation environment
- Applicable standard or utility specification
- Required inspection reports and material certificates
- Order quantity, marking and packaging
Frequently Asked Questions
What does an MRJ twin-bundle spacer do?
It maintains a specified distance between two parallel subconductors and helps limit conductor contact and excessive relative movement.
Is this a vibration-damping spacer?
Not necessarily. The pictured structure appears to be a rigid metal spacer without visible elastomer damping components. Damping performance must not be claimed unless it is supported by the exact product design and test report.
Can one spacer fit every conductor size?
No. The conductor groove must match the actual conductor outside diameter. An incorrect groove may allow slipping or cause excessive local pressure on the conductor.
Can the bundle spacing be customized?
Yes. Center-to-center spacing can be manufactured according to the approved drawing, provided that the mechanical design and conductor compatibility are verified.
Can it be used in substations?
Yes. MRJ series spacers are commonly selected for twin-bundle flexible-bus arrangements in substations and switchyards. The exact model must match the bus conductor and project design.
