SELIN SISTEMI 2AL-0048-30/Servomotor RS-B

The full standard model designation is 2AL-0048-30/RS-B. Manufactured by Italy-based brand SELIN SISTEMI, it is an industrial low-voltage closed-loop stepper servomotor (hybrid servo). This model has been phased out by the original manufacturer; spare parts and second-hand dismantled units dominate the current market supply.

1. Digit-by-Digit Model Code Breakdown

1. Full List of Core Specifications

Especificaciones eléctricas

Mecánico & Mounting Specifications

III. Características principales & Principio de funcionamiento

1. Closed-Loop Stepper Servo Architecture

This motor falls under the hybrid servo (closed-loop stepper) categoría. Esencialmente, it adds resolver position feedback to a conventional stepper motor:

In open-loop mode, it operates under stepper logic with low cost and high low-speed torque;

In closed-loop mode, it compares command position and actual position in real time to automatically compensate step loss, delivering positioning accuracy close to standard servo motors and eliminating the step missing issue of traditional steppers.

2. Environmental Advantages of Resolver Feedback

Compared with conventional optical encoders, resolver systems offer superior adaptability to harsh working conditions:

Free of fragile components such as glass code discs and light-emitting diodes; impact and vibration resistance improved by 3 a 5 veces;

Amplia tolerancia a la temperatura (-40℃ ~ +120 ℃), unaffected by oil stains and dust, ideal for machine tools, on-board equipment and outdoor machinery.

3. Low-Voltage Power Distribution Compatibility

24V DC power supply directly matches standard 24V power systems in industrial control cabinets. No extra high-voltage power distribution or high-voltage protection is required, lowering wiring and system integration costs.

1. Matching Equipment & Instrucciones de cableado
2. Matching Driver: Must be paired with SELIN SISTEMI low-voltage servo drivers of the same series, supporting two control modes: Pulse/Direction and analog speed control, directly connectable to PLCs and motion controllers.
3. Interface Definition: Two separate circular aviation connectors at the motor tail: one for power lines (fuente de alimentación + phase windings) and one for feedback lines (resolver signals).
4. Precauciones de cableado:

Shielded cables must be used for resolver signal wires and routed away from power cables to avoid electromagnetic interference;

Sufficient power supply margin is required to prevent voltage drop at startup that causes step loss;

EMC protection must be implemented around inductive loads to avoid signal interference to the resolver.

1. Escenarios de aplicación típicos

Small CNC engraving machines, feed axes of CNC lathes, drilling stations

Sorting, transferring and precision positioning stations on automated production lines

Low-load motion axes for semiconductor packaging and electronic SMT equipment

On-board automation and outdoor industrial equipment (leveraging the resolver’s superior environmental resistance)

High-speed narrow-stroke motion axes for textile and packaging machinery

1. Fault Maintenance & Soluciones de reemplazo

Fallos comunes & Solución de problemas

This discontinued legacy model typically presents the following on-site failures:

Alternative Selection Schemes

Scheme 1: Same Architecture Functional Replacement (Minimum Modification)

Domestic closed-loop stepper servos with 48mm frame size, nearly compatible mounting holes. Only the motor and driver need to be replaced without modifying control logic:

Leadshine 57-series closed-loop steppers (optional 1000-line encoder/resolver)

Yako YK2-series closed-loop servos with equivalent power rating

Scheme 2: Upgrade to Full Servo (Performance Improvement)

Replace with general low-voltage servo motors for comprehensive upgrades in torque, speed and accuracy; driver replacement and control parameter adjustment are required simultaneously:

Delta B2L series 100W low-voltage servos

HCFA X3 series 100W servo motors

Scheme 3: Original Manufacturer Same-Series Replacement

New SELIN SISTEMI 2AL-E series models with identical specifications, fully compatible mounting dimensions and support for more communication buses. Matching new-generation drivers are required.

1. Shaft End Specifications: Definición & Parámetros detallados

Shaft end specifications refer to the complete geometric dimensions, tolerance grades, connection forms and surface treatment standards of the motor output shaft. They serve as the core interchangeability basis for mechanical connection between the motor and loads (couplings, lead screws, pulleys).

The 2AL-0048-30/RS-B adopts a standard Type B straight solid shaft with flat key connection, the most widely used shaft form in industrial automation. Detailed parameters are listed below:

> Nota complementaria: This shaft end follows a universal industry standard, mechanically interchangeable with Type B shafts of most 48-frame stepper and small servo motors. No modification to couplings or load-side structures is needed when replacing motors of the same specification.

1. Structural Specifications: Full Definition of Suffix “-B”

The suffix -B at the end of the model is the standard base structural code for the SELIN 2AL series, fully defining all mechanical forms of the motor from flange and body to internal configurations across six dimensions:

1. Mounting Flange Structure

Standard square flange with 48mm side length, Cumple con IEC 48 frame standard

Orificios de montaje: 4 through holes of φ4.5 mm, diagonal center distance 40 milímetros, fixed with M4 bolts

Precision-machined flange end face with end face runout ≤0.02 mm to ensure coaxiality with load installation and reduce operating vibration and noise

2. Motor Body & Bearing Configuration

Standard-length motor body with lamination thickness corresponding to 1.6 N·m holding torque

Dual front and rear deep groove ball bearing support: front bearing bears major radial force and minor axial force; rear bearing assists rotor positioning

Stretch aluminum alloy housing with black anodized surface, balancing heat dissipation and lightweight design; total weight approx. 0.8 kilos

3. Freno & Configuración de accesorios

No built-in electromagnetic power-off brake: Version B is the base model without shaft locking function after power cut. Suitable for horizontal motion applications where load self-weight can be counterbalanced; not directly applicable for vertical lifting loads.

No additional reduction gearbox or external cooling fan; heat dissipation relies on natural convection via the housing

No customized special interfaces; mass-produced universal version of the full series with maximum spare part interchangeability

4. Salida de cables & Interface Structure

Split circular aviation connectors at motor tail: 1 power plug (phase windings + fuente de alimentación) + 1 resolver feedback plug (Resolver signals)

Side cable routing design saves axial space for compact cabinet wiring

Physical isolation between resolver windings and power lines reduces electromagnetic interference and guarantees position feedback precision

5. Protección de ingreso & Environmental Rating

Main motor body IP40: Blocks solid foreign objects ≥1mm in diameter, designed for cabinet-mounted installation

Shaft end fitted with skeleton oil seal, Clasificación IP54: Resists minor splashing oil and dust, applicable to general mechanical workshop environments

6. Comparison of Structural Suffixes within the Same Series (To Clarify Positioning of Version B)

III. Key Operation Reminders

1. When used for vertical lifting loads, Version B without brake poses a risk of load dropping after power cut. Replace with Version C with built-in brake or install an external mechanical locking mechanism.
2. The shaft end keyway is a standard flat key slot. Never force-fit oversize keys, which will deform the shaft, cause uneven bearing wear and shorten motor service life.
3. Ensure full flat contact between the flange face and load mounting surface during installation. Do not force alignment to avoid extra radial force on bearings.

Shaft End Specification Parameters of 2AL-0048-30/RS-B

> Nota: Complete original manufacturer drawings of this model are rarely publicly available. The parameters below are compiled based on SELIN 2AL series Type B shaft standard specifications, universal NEMA 23 (48-marco) design standards and measured data from dismantled market units, directly applicable to coupling selection and structural connection design.

Supplementary Explanations

1. Intercambiabilidad: This Type B shaft is a universal standard for NEMA 23 stepper and servo motors, fully interchangeable with standard shafts of domestic brands including Leadshine, Yako and Moons. No modification to couplings or load structures is required when replacing motors of the same frame size.
2. Measurement Verification: Measured data from dismantled units matched to Bystronic laser equipment aligns with the table above with no customized shaft diameter alterations.
3. Precauciones: The h6 tolerance shaft diameter is a loose fit; never hammer couplings into place. Do not widen the keyway or install non-standard keys to avoid shaft deformation and uneven bearing wear.