780 series (2-pole 40 A)
Mars / JARD · DP 40 A frame
Wholesale-counter standard 40 A definite-purpose contactor. The 24 VAC coil version (e.g. Mars 17447/61447) is the most-stocked contactor in HVAC.
Ratings
- FLA (inductive)
- 40 A @ 240–600 V
- LRA (locked rotor)
- 240 A @ 240 V · 200 A @ 480 V
- Resistive
- 50 A
- Single-phase HP
- 3 HP @ 115 V · 7.5 HP @ 230 V
Coil data
- Available coil voltages
- 24 VAC, 120 VAC, 208–240 VAC
- Inrush VA
- ≈ 31–40 VA
- Sealed (holding) VA
- ≈ 5–6 VA
- Pickup voltage
- ≥ 85% of rated
- Dropout voltage
- 20–65% of rated
Typical measured coil resistance (±15%, ballpark)
24 VAC≈ 8–13 Ω
120 VAC≈ 180–320 Ω
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.
Ω
This model (24 VAC table value)8 Ω–13 Ω
Generic mid-frame 24 VAC4 Ω–9 Ω
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.
Terminals & accessories
Power/coil terminals: Box lugs accept 14–8 AWG; coil tabs are 1/4 in. quick-connects
Auxiliary contacts: Some SKUs offer a 1-SPST auxiliary switch piggyback; not universal — check the box
Cross-references
- Packard C240A
- Titan TPD402C
- Eaton C25BNB240
- Siemens 42BF35AG (3-pole cousin)
Field notes
- Quick-connect coil terminals vibrate loose on reciprocating compressors — crimp properly and tug-test every one.
- If the new coil burns out in days, find the cause: low control voltage, coil rated 24 V sitting on 28+ V, or mechanical binding in the armature.
Mars / JARD resources
Links go to the manufacturer's current catalog or product page — model-specific pages are often retired, so these stay live.