CWB18 (3-pole 18 A)
The workhorse 18 A CWB — the default contactor on 5 HP class compressor packages and small rotary screws built on WEG motors, and increasingly common as OEM equipment on Brazilian-built packages (Schulz etc.). Shares the compact 45 mm frame with CWB9–25.
- AC-3 (440 V)
- 18 A
- AC-1 (resistive)
- 32 A
- Hp (3Φ)
- 5 HP @ 230 V · 10 HP @ 460 V
- Hp (1Φ)
- 1.5 HP @ 115 V · 3 HP @ 230 V
- Single-phase HP
- 1.5 HP @ 115 V · 3 HP @ 230 V
- Three-phase HP
- 5 HP @ 230 V · 10 HP @ 460 V
- Available coil voltages
- Suffix-coded coil: 24, 120, 208–240, 480 VAC 50/60 Hz; 24 VDC and electronic wide-range versions
- Inrush VA
- ≈ 65 VA
- Sealed (holding) VA
- ≈ 7.5 VA
- Pickup voltage
- ≥ 80% of rated
- Dropout voltage
- ≈ 40–65% of rated
OL = open coil · near zero = shorted turns · coil-to-frame must read >1 MΩ.
Coil resistance checker
Pick the coil voltage, enter your meter reading across A1–A2 (coil disconnected), and compare it to the expected ballpark.
OL = open coil. 0–2 Ω = shorted turns (often from a cooked transformer). Ballpark only (±15%+); electronic wide-range coils (e.g. ABB AF) read misleading values — test those at rated voltage instead. Always measure coil-to-frame too: must be >1 MΩ.
- Schneider LC1D18
- Siemens 3RT2025/26 (S0)
- ABB AF16 / A16
- Allen-Bradley 100-C23
- Eaton XTCE018C
- Legacy: WEG CWM18 / CWM25
- Same physical frame for CWB9/12/18/25 — swapping up an amp rating is a one-screw job when a motor gets upgraded, as long as the overload range covers the new FLA.
- If the machine is a Schulz compressor, the whole control chain (contactors, overload, push buttons) is likely WEG — keep one line of spares.
- Buzz after years of service usually means dirt on the armature pole faces; wipe with a dry cloth only — never solvent or a file.
- RW27 dial range must cover motor FLA AND service-factor amps; WEG motors commonly run 1.15 SF.
Links go to the manufacturer's current catalog or product page — model-specific pages are often retired, so these stay live.