ULV 1200 Power Resistor Datasheet: Full Specs & Limits
The ULV 1200 is a 1200 W-class metal-clad, wire-wound power resistor engineered for heavy steady dissipation and demanding braking/load-bank duties. This technical guide breaks down the nominal 1200 W continuous capability, low-ohm high-current options, and pulse energy limits critical for industrial power systems.
1 — Product Background & Construction
Design Essentials
The ULV 1200 features a wire-wound resistive element housed in a ventilated metal-clad enclosure. This construction provides high thermal mass and predictable conduction paths. Non-inductive styles are available to reduce series reactance for fast transient loads or DC applications.
Typical Application Scenarios
Primary uses include dynamic braking for motor drives, industrial load banks, and inrush current limiting. It is designed for installation within ventilated cabinets or outdoor enclosures where energy absorption must be strictly controlled.
2 — Electrical Specifications
The following table summarizes core parameters for typical ULV 1200 configurations. Rated current (I) is derived from the formula I = sqrt(P/R).
| Model Variant | Resistance (Ω) | Rated Power (W) | Max Current (A) |
|---|---|---|---|
| ULV-1200-0.1 | 0.1 | 1200 | 109.5 |
| ULV-1200-1.0 | 1.0 | 1200 | 34.6 |
| ULV-1200-10 | 10.0 | 1200 | 10.9 |
| ULV-1200-100 | 100.0 | 1200 | 3.4 |
3 — Thermal Behavior & Derating
The 1200W rating is valid up to a specific ambient temperature (typically 25°C or 40°C depending on airflow). Beyond this, a derating curve must be applied. If your enclosure ambient reaches 70°C, the allowable power may drop to 60-80% of the nominal rating. Always verify the specific curve in the manufacturer PDF and provide adequate clearance for convective cooling.
4 — Mechanical & Mounting Requirements
For optimal performance, mount the ULV 1200 with the housing vertical to promote natural convection. Ensure all terminals are torqued to manufacturer specifications to prevent contact resistance heating. Minimum free-air clearance should equal the unit's height on all hot faces.
5 — Verification & Troubleshooting
Field Test Checklist
- Measure DC resistance to ensure it is within specified tolerance (e.g., ±5% or ±10%).
- Perform a staged power soak while monitoring surface temperatures with thermal imaging.
- Check insulation resistance (Hipot) between terminals and the metal chassis.
6 — Selection Checklist
- Continuous Power: Does the 1200W rating include a safety margin?
- Inductance: Is a non-inductive winding required for high-speed switching?
- Environment: Does the installation require forced airflow or a specific IP rating?
Frequently Asked Questions
What is the rated current of a ULV 1200 for a given resistance?
Compute rated current using the formula I = sqrt(P/R). For a 1.0 Ω resistor at 1200 W, the rated current is approximately 34.6 A. Maximum continuous voltage is then V = I × R, or 34.6 V in this example.
How should I interpret the ULV 1200 derating curve?
Locate your maximum expected ambient temperature on the x-axis of the datasheet's derating graph. The corresponding y-axis value indicates the percentage of the 1200W rating that can be safely dissipated. If the enclosure ambient is high, you must de-rate accordingly.
What field tests validate ULV 1200 performance after installation?
Key tests include baseline DC resistance measurement, a thermal soak test to identify hotspots, and a verification of terminal torque. Monitoring the resistance drift over time can help predict end-of-life or overheating issues.
When is a non-inductive (Aryton-Perry) winding necessary?
Specify the non-inductive variant when the resistor is used in high-frequency circuits, fast-pulse applications, or any scenario where the inherent inductance of a standard wire-wound resistor would cause unwanted voltage spikes or signal distortion.
