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Kollmorgen B-204-C-31-B3
Overview:
The B-204-C-31-B3 is a regenerative braking unit (brake chopper) from the Kollmorgen B-200 product series. Unlike a passive braking resistor (B-600 series), the B-204 is an active electronic module that switches the DC bus energy to an external braking resistor with precise duty-cycle control. The model code: B-204 (B-200 series, 4 kW class) + C (configuration variant) + 31 (specific electrical rating) + B3 (terminal/connector variant). This unit is used in applications with high regeneration duty cycles where precise DC bus voltage clamping is required.
Detailed content
Key Specifications:
| Parameter | Value |
|---|---|
| Rated Power Handling | Up to 4 kW regenerative (with external resistor) |
| Input Voltage Range | 200–480 VAC (3-Phase) |
| DC Bus Clamping Voltage | Adjustable: 380–565 VDC |
| Max Braking Current | 20 A continuous (with adequate resistor) |
| Switching Frequency | 16 kHz PWM |
| Control Interface | Analog (0–10 V) or internal voltage threshold |
| Enclosure Rating | IP20 (chassis mount) |
| Operating Temperature | 0°C to +45°C (derate above 40°C) |
| Dimensions (W×H×D) | Approximately 100 × 150 × 120 mm |
| Weight | Approximately 1.2 kg |
Material Composition:
- Power Electronics: IGBT modules (rated 600 V / 40 A)
- Heat Sink: Extruded aluminum with forced-air cooling (internal fan)
- PCB: FR-4, conformal coated, with isolated gate drivers
- Terminals: Screw terminals with safety spacing per IEC 61800-5-1
- Enclosure: Steel or aluminum, powder-coated
Structural Features:
- DIN-rail or chassis mount
- Integrated cooling fan with filter
- Terminal blocks: DC bus input (P/N), braking resistor output (B+/B-), control signal input
- LED indicators: Power, Fault, Braking Active
- Adjustable potentiometer for DC bus clamping voltage setpoint
Working Principle:
The B-204 monitors the DC bus voltage in real time. When the voltage exceeds the user-set threshold (e.g., 420 VDC), the IGBT switches on at 16 kHz PWM frequency, routing current from the DC bus to the external braking resistor. The duty cycle is modulated to maintain the DC bus voltage at the setpoint — this is far more precise than a simple transistor switch (as in the B-600 passive resistor approach). The result is tighter voltage regulation, lower peak voltages, and the ability to use a smaller external resistor for the same application.
Advantages:
- Active voltage clamping — maintains DC bus within ±5 V of setpoint (vs. ±30 V for passive)
- Smaller external resistor required — saves space and cost in the cabinet
- Adjustable threshold — adapts to different system voltages and regeneration profiles
- Built-in fan cooling — handles higher duty cycles than passive chopper modules
- Compatible with all Kollmorgen S700 and AKD drives
Applicable Industries:
High-inertia CNC spindles, large gantry systems, crane and hoist drives, wind turbine pitch systems, large conveyor systems, testing rigs with rapid reversal.
Installation Requirements:
- Mount with adequate airflow (minimum 50 mm clearance on fan side)
- Connect external braking resistor using minimum 10 AWG (6 mm²) cable
- Set DC bus clamping voltage via front-panel potentiometer or analog input
- Connect to drive’s braking transistor output terminals (B+/B-)
- Ensure drive parameter “Brake Type” is set to “Active/Chopper”
Usage Precautions:
- Never operate without an external braking resistor connected — the IGBT will be destroyed by uncontrolled DC bus overvoltage
- Verify resistor wattage matches calculated regeneration: P_regen = 0.5 × J × ω² / t_decel
- The internal fan has a service life of approximately 40,000 hours — plan for replacement
- Do not exceed 480 VAC input — IGBT breakdown voltage is 600 VDC with no margin for transients above 480 VAC input
