ULV 300 N 70 J datasheet: full specs, ratings & charts
🚀 Key Takeaways
- 300W Power Density: Handles massive energy loads in compact footprints, saving 15-20% cabinet space.
- ±5% Precision (J-Code): Ensures consistent braking torque and predictable snubber performance.
- Wire-Wound Durability: Superior transient surge survival compared to standard film resistors.
- Flexible Mounting: Optimized for both free-air convection and high-efficiency heatsink cooling.
This article distills the datasheet technical data for the ULV 300 N 70 J into a single, actionable reference — full specs, electrical and thermal ratings, derating charts, and selection guidance. It is designed for US engineering teams requiring a compact, datasheet-tied summary for design documentation and rapid part verification.
1 — Product Overview & Naming Decode
Figure 1: ULV Series Industrial Power Resistor Profile
Decoding the ULV 300 N 70 J
The ULV 300 N 70 J identifies a wire-wound, high-power dissipation resistor optimized for harsh electrical environments. Converting technical codes into engineering reality:
- ULV 300: 300W Nominal Power Class (Handles high-energy braking without thermal runaway).
- Token N: Specific resistance marker defined in the datasheet resistance table.
- J Code: ±5% Tolerance (Balances cost with high-accuracy load requirements).
- FL=1000: 1000mm Lead finish/mounting suffix (Flexible installation in large drive cabinets).
Competitive Differentiation
| Feature | ULV 300 N 70 J | Standard Ceramic Resistor | User Benefit |
|---|---|---|---|
| Power/Size Ratio | High (300W Class) | Low/Medium | 20% PCB/Panel space saving |
| Surge Capability | Excellent (Wire-wound) | Moderate | Prevents failure during peak braking |
| Thermal Stability | < 260 ppm/°C | > 400 ppm/°C | Consistent performance across Temp |
2 — Full Technical Specifications & Electrical Ratings
Designers should apply a 20–30% safety margin from rated power for extended service life in unventilated enclosures.
| Parameter | Value (Reference Only) | Datasheet Ref |
|---|---|---|
| Nominal Resistance | [Ω — Check N-Token Table] | Table 3 |
| Tolerance | J = ±5% | Electrical Specs |
| Rated Power (Free Air) | 300 W @ 25°C | Table 4 |
| Rated Power (Heatsink) | Higher (See Mounting Fig. 4) | Thermal Ratings |
| Max Working Voltage | Check specific Series Limit | Safety Ratings |
3 — Thermal Performance & Derating Curves
Temperature management is critical. The ULV 300 series relies on the Derating Curve (Datasheet Fig. 6) to maintain integrity at elevated ambient temperatures.
How to Calculate Allowable Power:
P_allowed = P_rated × Derating_Factor
T_junction = T_ambient + (P_actual × Rth)
Note: Rth (Thermal Resistance) varies based on mounting orientation and airflow.
👨💻 Engineer's Insights & Best Practices
By: Dr. Julian Vance, Senior Systems Design Engineer
PCB Layout Tip: For high-wattage components like the ULV 300, avoid placing sensitive logic ICs or electrolytic capacitors within a 50mm radius. The radiant heat can significantly reduce the MTBF of surrounding components.
Common Pitfall: Many designers ignore lead inductance in high-speed snubber applications. While wire-wound resistors are robust, for ultra-fast switching (MHz range), verify if the non-inductive winding option is required.
Hand-drawn sketch, not a precise schematic
Typical Application: Braking Chopper
Connect the ULV 300 between the DC bus and the switching IGBT to dissipate regenerative energy from the motor.
4 — Installation & Maintenance Checklist
- Mounting: Use high-temperature thermal interface material (TIM) if attaching to a metal chassis.
- Torque: Follow Datasheet Table 8 for fastener torque to prevent stress-cracking of the ceramic core.
- Monitoring: Periodically check for Insulation Discoloration—the first sign of chronic thermal overstress.
- Validation: Run an 8-hour "Power Soak" test at 100% of the planned load to ensure ΔR (resistance drift) stays within the ±2% operational limit.
Summary of ULV 300 N 70 J
The ULV 300 N 70 J is a high-reliability power solution for demanding industrial loads. By integrating the 300W power class with a robust wire-wound construction, it provides the safety margins necessary for motor drives and power conversion systems. Always cross-reference your thermal model with the Datasheet Fig. 6 derating curve and Fig. 5 pulse rating chart before final procurement.
