The LTi SO84.250 is a flagship ultra-high-power three-phase servo drive in the BG7 housing, delivering 250A continuous and 425A peak current. With mandatory liquid cooling, it is designed for the most extreme industrial single-axis applications.
Rated current: 250 A (400V, 2 kHz switching frequency), peak: 425 A (0-5 Hz)
Mains: 3 x 230V to 480V AC ±10%
Switching frequencies: 2 kHz, 4 kHz
BG7 dimensions: width 380 mm, height 952 mm, depth 286.5 mm, weight 100 kg
External mains choke mandatory (uk = 2%)
External precharging circuit required
Integrated brake chopper with optional internal braking resistor
Rated current: 250 A (400V, 2 kHz), 231 A (480V)
Peak current: 425 A (0-5 Hz)
Connected load: 173 kVA
Power loss at IN: 3960 W (2 kHz, liquid-cooled)
DC link capacitance: 3600 μF
Brake chopper threshold: 820 V DC
Minimum external braking resistor: 3.2 Ω
Continuous braking power (external): 210 kW
Peak braking power: 210 kW
Optional internal braking resistor: 3.3 Ω, continuous 5000 W, peak 204 kW
Nominal coolant flow: 11 l/min (max 13 l/min)
Coolant pressure: 1 bar nominal / 2 bar max
Coolant temperature: 5°C to 40°C
Coolant quality: drinking water + corrosion inhibitor
Shutdown at 65°C heat sink
Control supply: 24 V DC ±10% (4A start, 2A continuous)
Separate precharge circuit (X45) with external contactors K1, K2, K3
Digital I/O: 6 inputs, 3 outputs, relay
Analog inputs: 2 differential (±10V)
Resolver and high-resolution encoder
Motor brake output: 24V/2A (X44)
USB, Ethernet, MMC, option slots

The BG7 requires careful installation. Connect the liquid cooling circuit with 3/8 inch female threads. The external precharging circuit (see manual) must be wired using contactors K1 (mains), K2 (precharge), and K3 (relay). The control sequence first precharges the DC link via X45, then closes the main contactor. Use shielded motor cables with ring terminal ends (M12 screws). The external mains choke is mandatory.
Commission with DriveManager 5. After applying 24V control supply (X44), the precharge sequence must be completed before enabling the power stage. The 7-segment display shows status. STO inputs (ISDSH and ENPO) must be at +24V to release the power stage. Parameter sets can be stored on MMC card.
The internal brake chopper handles up to 210 kW continuous with external 3.2 Ω resistor. The optional internal braking resistor (3.3 Ω) provides 5 kW continuous and 204 kW peak. Always monitor resistor temperature with a bimetal switch wired to a digital input.
Suitable for servo motors up to 132 kW (400V). Typical applications include large presses, steel rolling mills, heavy-duty test benches, wind turbine main drives, and marine propulsion systems.
Complies with EN 61800-5-1, EN 61800-3, LVD, EMC. UL approval for BG7 is planned.
The LTi SO84.250 delivers unparalleled power for the most demanding single-axis servo applications.



