The Compact Flameproof Power Wirewound Resistors WP-S series is a small-sized power resistor with enhanced pulse handling capability and flameproof protection. It is available in SMD Z-form and complies with RoHS requirements. Welwyn Components reserves the right to make changes in product specification.
The WP‑S Series offers compact, flame‑proof wirewound resistors with power ratings from 1 W to 7 W at 25 °C and enhanced pulse‑handling capability. Electrical data include resistance ranges from 8 Ω to 10 kΩ, limiting element voltages up to 150 V, and isolation voltages up to 700 V.
Construction uses a high‑purity ceramic substrate with interference‑fit end caps and a flame‑proof silicone coating. The series is available in radial, goalpost, lancet, and SMD Z‑form packages, with optional packaging in taped reels, boxes, or loose plastic bags. Application notes cover derating, lead spacing, and thermal impedance calculations.
| Power rating at 25 °C | 1 W (WP1S), 2 W (WP2S), 2.5 W (WP25S), 3 W (WP3S), 4 W (WP4S), 5 W (WP5S), 7 W (WP7S) |
|---|---|
| 5 s overload rating at 25 °C | 5 W (WP1S) – 35 W (WP7S) |
| Resistance range | 8 Ω to 10 kΩ (various series) |
| Limiting element voltage | 50 V – 150 V |
| Temperature coefficient (TCR) | <350 ppm/°C (≤1 Ω), <200 ppm/°C (>1 Ω) |
| Isolation voltage | 250 V – 700 V |
| Ambient temperature range | -55 °C to +155 °C |
| Thermal impedance | 140 °C·W to 85 °C·W (depending on size) |
| WP1S dimensions (L×D) | 6.2 mm × 2.8 mm |
Terminations should be soldered at least 4 mm away from the body.
They can operate from –55 °C up to +155 °C.