Description
Bosch Rexroth LT-304 — Power Supply Module
The LT-304 (part number typically 0 608 750 085) is a power supply module manufactured by Bosch Rexroth for the IndraDrive drive and control platform. It serves as the electrical power backbone for Rexroth’s servo drive and motion control systems, converting incoming AC mains power into stable DC bus voltage that feeds the servo amplifiers.
Rexroth LT304 Controller Module 0608750085
What It Does
The LT-304 takes three-phase AC input (typically 380–480 VAC, 50/60 Hz) and converts it to a regulated DC bus voltage (usually around 540–650 VDC depending on configuration). This DC bus then powers the connected servo drive modules — such as the HCS02, HCS03, or IndraDyn S series amplifiers — which in turn drive the servo motors. Without the LT-304, the drives have no power. It is essentially the “heart” of the electrical supply chain in a Rexroth drive cabinet.
Key Technical Specifications
| Parameter | Value |
|---|---|
| Input voltage | 3 × 380–480 VAC (±10%), 50/60 Hz |
| Output DC bus | Adjustable, typically 540–650 VDC |
| Rated power | Up to approximately 15–30 kW (varies by configuration) |
| Power factor correction | Integrated active PFC — meets IEC 61000-3-12 harmonic standards |
| Efficiency | >95% typical |
| Protection | Over-voltage, under-voltage, over-current, short-circuit, over-temperature |
| Cooling | Forced air (integrated fan) |
| Mounting | DIN rail or chassis slot in IndraDrive cabinet |
| Dimensions | Approximately 200 × 150 × 100 mm (varies) |
| Weight | Roughly 2–4 kg |
| Operating temperature | 0°C to +50°C (derating above 40°C) |
| Protection rating | IP20 (cabinet mounting) |
| Compliance | CE, UL, CSA, TÜV certified |
How It Fits in the System
A typical IndraDrive cabinet layout:
AC Mains (3-phase) → LT-304 Power Supply → DC Bus (540–650 VDC) → Servo Amplifier (HCS02/HCS03) → Servo Motor
Multiple LT-304 modules can be installed in one cabinet to support multi-axis systems — each module feeds its own DC bus section, ensuring that a fault on one axis does not take down the entire machine. The module also communicates with the IndraWorks engineering software via the drive bus, reporting voltage, current, temperature, and fault status in real time.
Compatible Systems
The LT-304 works with virtually all Rexroth IndraDrive platforms:
- IndraDrive C — compact servo drives for single-axis applications
- IndraDrive Cs — modular multi-axis servo system
- IndraDrive M — motor-integrated drives
- IndraDyn S — synchronous servo drives
- HCS02 / HCS03 — classic servo amplifier modules
- CSH01 — single-axis servo drives
It is also compatible with Rexroth’s CML and CML Motion Logic controller families for coordinated multi-axis motion.
Key Features
Active Power Factor Correction (PFC) — The LT-304 includes built-in PFC circuitry, keeping input current harmonics well below IEC 61000-3-12 limits. This means cleaner power draw from the plant supply, reduced transformer heating, and no need for external harmonic filters in most installations.
Soft-start function — On power-up, the LT-304 ramps the DC bus voltage gradually (typically over 2–5 seconds), eliminating inrush current spikes that could trip upstream breakers or stress the AC supply.
Redundancy support — In critical applications (CNC machines, presses, printing), two LT-304 modules can be configured in parallel with automatic switchover — if one fails, the other takes over within milliseconds, preventing machine downtime.
Diagnostics and monitoring — The module reports DC bus voltage, output current, internal temperature, fan status, and any fault conditions via the IndraDrive communication bus. All data is visible in IndraWorks and can be logged to SCADA/PLC systems.
Compact and modular — The unit fits standard IndraDrive chassis slots and can be hot-swapped in redundant configurations (with proper sequencing).
Typical Applications
- CNC machine tools — lathes, mills, grinders (multi-axis servo systems)
- Packaging machines — high-speed pick-and-place, forming, sealing
- Printing presses — web tension control, register synchronization
- Metal forming — press lines, stamping, bending
- Plastics machinery — injection molding, extrusion
- Material handling — conveyor systems, AGVs, palletizers
- Robotics — multi-axis robot servo drives
- Textile machines — winding, weaving, knitting
Status & Availability
The LT-304 is an active, supported Bosch Rexroth product — not obsolete. It remains widely used in existing IndraDrive installations globally and is still manufactured. New units typically ship in 4–8 weeks from Rexroth authorized distributors; stock items may ship within 1–3 days.
Pricing varies significantly by region and configuration but generally falls in the range of ¥3,000–10,000 RMB (~420–1,400 USD) depending on power rating and options. Refurbished units are available from third-party industrial automation suppliers at 40–60% discount.
Common distributors in China include Rexroth direct sales offices, local authorized partners in Shanghai, Shenzhen, and Beijing, as well as specialized DCS/drive spare parts dealers.
Common Issues & Maintenance
- Fan failure: The internal cooling fan is the most common wear item. Replace annually or when noise increases — overheating will trigger thermal shutdown and eventually damage internal capacitors.
- Capacitor aging: Electrolytic capacitors on the DC bus degrade over 5–8 years. Watch for DC bus voltage ripple increasing — this is a sign of capacitor wear.
- PFC circuit faults: If the module trips on input over-current, check the PFC section — a failed IGBT or diode in the PFC stage is a common fault.
- Firmware: Rexroth periodically releases firmware updates for improved PFC algorithms and protection thresholds — check with your local Rexroth service office.
- Backup configuration: Always save the IndraWorks project file — if the LT-304 fails and is replaced, you can re-flash the cabinet configuration in minutes.
Bottom Line
The Bosch Rexroth LT-304 (0 608 750 085) is the power supply workhorse of the IndraDrive platform — converting three-phase AC mains into clean, stable DC bus power for servo amplifiers and motors. With active PFC, soft-start, redundancy capability, built-in diagnostics, and full IndraWorks integration, it delivers reliable, efficient power to CNC machines, packaging lines, presses, robots, and virtually every motion control application where Rexroth drives are used. Actively manufactured, globally supported, and a proven component in millions of installations worldwide.
