General Information

Core Description

VRDM397/50LNB is a high-precision 3-phase stepping motor designed for stable and accurate positioning control in industrial automation systems. It features a compact size 90 flange design with 70 mm stator length, operates on 130 V supply, and provides 2.26 Nm holding torque. Equipped with an integrated spring-pressure holding brake and class F insulation, it ensures secure axis retention and reliable performance even during power loss or emergency stop conditions.

Specific Application

• Vertical Axis Handling Equipment: Securing vertical Z-axis loads against gravitational drop inside compact pick-and-place automation cells using the internal 24V spring-pressure brake.
• Space-Constrained Positioning Infeeds: High-torque angular indexing inside industrial machinery footprints where the mounting flange profile cannot exceed 90 mm.
• Multi-Step Angular Actuation: Running deterministic positioning paths via calibrated step divisions ranging from 200 up to 10000 steps per revolution.

Ordering Information

System Compatibility

The VRDM397/50LNB motor is fully compatible with standard SIG Berger Lahr 3-phase power drives, including the D 900 series stepping controllers configured for 130 VDC operation. It interfaces seamlessly via standard pre-assembled industrial motor power cables and utilizes a specialized Hirschmann type G4 A 5M polarized connection plug to control the integrated 24 VDC electromagnetic holding brake system.

Alternative Model: VRDM397/50LHB

Within the same mechanical size 90 footprint, the VRDM397/50LHB serves as the heavy-current, low-voltage alternative model.

Key Technical Differences

• Winding Classification and Operating Voltage
  The VRDM397/50LNB features a normal winding (LN) optimized for 130 V systems, whereas the VRDM397/50LHB uses a heavy-current winding (LH) engineered for low-voltage 40 V drive operation.
• Current and Torque Outputs
  The normal winding variant runs at a lower rated current of 4.4 A to produce a 2.26 Nm holding torque, while the heavy-current alternative draws a higher current of 5.5 A resulting in a slightly lower holding torque profile of 1.92 Nm.
• Winding Resistance and Response Constants

The VRDM397/50LNB possesses a winding resistance of 1.0 alongside a 7 ms current rise constant, whereas the LH version exhibits a lower internal resistance of 0.35 to adapt to low-voltage driver output stages

• Brake Integration and Suffix Profile
  The current model features an integrated 6 Nm mechanical holding brake, while the alternative LHB suffix indicates a bare heavy-current motor lacking pre-installed braking hardware or secondary shaft extensions.

Installation & Troubleshooting FAQ

Q1: What is the mandatory load safety limit when deploying the VRDM397/50LNB on vertical Z-axes?

A: To guarantee that the electromagnetic spring-pressure brake holds reliably over its service life, the static load torque generated by the physical weight of the vertical assembly must never exceed 25% of the motor’s rated holding torque. Exceeding this margin risks axis slippage during emergency stops.

Q2: How can a field technician invert the physical rotation direction of the motor shaft?

A: The physical direction of rotation can be instantly reversed without altering driver software parameters by simply swapping the wiring locations of any two phase terminals (such as exchanging phase U with phase V, or phase V with phase W) inside the connection interface.

Q3: Why does the integrated holding brake require an overexcitation or dual-voltage circuit?

A: The holding brake requires a full 24 VDC excitation pulse to reliably disengage the mechanical springs during start-up. However, to prevent thermal buildup and motor overheating during prolonged runtime, the drive circuit should automatically lower the supply down to a reduced holding voltage level once the brake is disengaged.

Q4: Can an end-user replace the internal rotor bearings if they wear out prior to 20,000 hours?

A: No. The internal bearing must never be disassembled or replaced by the customer. Opening the motor core partially demagnetizes the internal permanent magnet structures. This causes an immediate, permanent loss of motor torque and positioning power.

Q5: What are the strict load limits regarding radial and axial shaft forces for this size 90 motor?

A: Under a nominal bearing life of 20,000 operational hours at 600 rpm, the front shaft end can support a maximum radial force of 100 N applied at a distance of 15 mm. The maximum admissible axial pull force is rated up to 170 N, while the maximum axial pushing limit is strictly capped at 30 N. Axial and radial loading forces must not occur simultaneously.