From the outside, choosing between a Leeson 5 HP AC motor and a Leeson DC motor looks straightforward—just match the specs to your application. The reality is that the real cost difference isn't in the upfront price tag, but in how each motor type behaves over its lifecycle.
I've managed procurement for a mid-sized packaging plant for about 7 years now. Our annual motor budget hovers around $85,000, and I've documented every single order, repair, and failure in our internal cost-tracking system. When I audited our 2023 spending, I found that the motors we picked based on initial quote actually cost us 18% more over 3 years than the alternatives we'd dismissed as "too expensive."
That's why I'm writing this—not as a sales pitch, but as a fellow buyer who's made the mistakes so you don't have to.
What We're Comparing and Why
This comparison focuses on two popular Leeson motor categories:
- Leeson 5 HP AC Motor (typically a 3-phase, TEFC, 1800 RPM unit)—the workhorse of industrial applications.
- Leeson DC Motor (typically a permanent magnet or wound-field, 1/8 HP to 2 HP range)—the precision variable-speed choice.
Why compare a 5 HP AC motor to a DC motor that's often smaller? Because in many real-world buy decisions—especially in packaging, material handling, and small automation—buyers are torn between the proven reliability of an AC induction motor and the flexibility of a DC motor. I've been in that room.
The comparison framework:
- Total Cost of Ownership (TCO) — upfront + energy + maintenance + downtime
- Performance & Control — How well does it handle variable loads?
- Maintenance & Diagnostics — What does real-world upkeep look like?
- Application Fit — When does one clearly win over the other?
Dimension 1: Total Cost of Ownership (TCO)
Upfront Cost
Leeson 5 HP AC motor: A new Leeson 5 HP, 3-phase, TEFC motor (model 140603.00 or similar) typically runs $1,200 to $1,800 depending on enclosure, efficiency rating, and frame size. That's from actual invoices I've processed.
Leeson DC motor: A comparable Leeson DC motor (say, a 1.5 HP permanent magnet unit) is often $800 to $1,200 for the motor alone. But here's the kicker—you need a DC drive (controller) to run it. That adds another $400–$800 depending on features. So the true upfront cost is often $1,200–$2,000—roughly equivalent to or slightly higher than the AC motor.
People assume the DC motor is cheaper because the motor itself is less expensive. What they don't see is the mandatory add-on cost of the drive.
Energy Cost Over 5 Years
Based on typical running hours in a production environment (say, 2,000 hours/year at 75% load):
- Leeson 5 HP AC (92% efficient): ~2.8 kW input × 10,000 hours × $0.12/kWh = $3,360
- Leeson DC motor (85% efficient with drive losses): ~1.3 kW input × same hours = $1,560
The DC motor wins on energy cost because it's variable-speed and runs at lower average load when not at full speed. But that savings narrows if your application runs the AC motor at full speed continuously—then efficiency curves are similar.
Verdict: DC motors often have lower 5-year energy cost in variable-speed applications. But AC motors maintain the edge in fixed-speed, continuous-duty scenarios.
Maintenance & Downtime Cost
This is where the comparison gets interesting (and painful, from experience).
Leeson 5 HP AC motor: These are brushless induction motors. The only wearing parts are bearings (and possibly a capacitor on single-phase versions). I've seen these run 8-10 years with just bearing replacements ($50-$120 every 2-3 years). Downtime: minimal—swap and go.
Leeson DC motor: Brushed DC motors have brushes that wear out. Depending on duty cycle, you're looking at brush replacement every 1,500–3,000 hours. Kit cost: ~$40-$80. Labor: a few hours. Plus, commutator wear may require a turn or replacement after 5,000–8,000 hours. Over a 5-year period, I'd budget $300–$600 for brush and commutator maintenance, plus associated downtime.
From the outside, it looks like DC motors are simpler to maintain. The reality is that brush maintenance adds recurring costs and unplanned downtime that AC motors simply don't have.
TCO Summary Table
| Cost Category | Leeson 5 HP AC | Leeson DC Motor (1.5 HP) |
|---|---|---|
| Upfront (motor + drive) | $1,200–$1,800 | $1,200–$2,000 |
| 5-Year Energy | ~$3,360 | ~$1,560 |
| 5-Year Maintenance | $200–$400 | $300–$600 |
| Total 5-Year TCO | ~$4,760–$5,560 | ~$3,060–$4,160 |
(Note: These are estimates based on my procurement records and typical running conditions. Your mileage will vary—always calculate with your actual load profile and electricity rate. Source: My internal cost tracking system, 2018–2024.)
Dimension 2: Performance & Control
Variable Speed Capability
Leeson 5 HP AC motor: You can add a VFD (Variable Frequency Drive) to get variable speed—but that adds $600–$1,200 upfront. Even then, AC motors have torque limitations at very low speeds (below ~5 Hz). They can overheat if run at low speed under full load for extended periods.
Leeson DC motor: Inherently variable-speed. Speed control is simpler and often more precise (down to near-zero RPM with full torque). The controller is simpler and cheaper than a VFD of equivalent power.
So glad I switched to a Leeson DC motor for our conveyor infeed section. Almost went with an AC + VFD combo to save $300 initially, which would have meant constant tuning headaches and a motor that ran hot at 10% speed.
Starting Torque
Leeson 5 HP AC motor: Starting torque is typically 150–200% of rated torque. Sufficient for most loads, but can cause mechanical stress on startup.
Leeson DC motor: Can deliver up to 300% of rated torque at startup. Excellent for high-inertia loads or applications requiring a soft-start without additional electronics.
Verdict: DC wins on variable-speed precision and starting torque. AC + VFD closes the gap but at higher cost.
Dimension 3: Maintenance & Diagnostics
Brushes and Commutators—The Weak Link
I'll be honest: this is the main reason many plants avoid DC motors. Brush dust accumulation, commutator wear, and the need for regular inspection—it's not rocket science, but it's a recurring task that AC motors don't require. In a production environment where "time is money," that matters.
Note to self: Remind the team to budget brush inspection for the DC motors in the packaging area—we've been running 3 years without checking them (ugh, that's going to be expensive).
Diagnostic Ease
Leeson 5 HP AC motor: Simple diagnostics. Megger test, winding resistance, bearing noise. If it fails, you replace it. Diagnosing a failed AC motor takes 15 minutes with a multimeter.
Leeson DC motor: More variables. Brushes worn? Commutator glazed? Field winding short? Drive fault? You need a bit more skill and equipment to isolate the problem. Not crazy hard, but requires a technician comfortable with DC systems.
Dimension 4: Application Fit (The Decision Guide)
When the Leeson 5 HP AC Motor is the Clear Winner
- Constant-speed applications: Fans, pumps, conveyors running continuously at fixed speed.
- Harsh environments: TEFC or explosion-proof enclosures are standard—AC motors handle dust, moisture, and temperature extremes better than DC motors generally.
- High-horsepower needs: 5 HP and above, AC is more cost-effective and readily available. DC motors above 5 HP get expensive fast.
- Low-maintenance priority: If your maintenance team is stretched thin, AC is the lower-effort option.
When the Leeson DC Motor is the Clear Winner
- Precision variable speed: Conveyor indexing, winding machines, printing presses, sewing machines—anything requiring speed control without a VFD.
- Battery-powered or mobile equipment: DC motors run directly on batteries (think: AGVs, floor scrubbers, lifts).
- Small form factor with high torque: When space is tight but you need high starting torque (e.g., small actuators, servo-like positioning without the servo price tag).
- Prototyping and low-volume runs: DC motors and drives are easier to interface with simple controllers. Great for startups and R&D—that 'small customer' friendly approach matters here.
Final Take: The Procurement Shortcut
Here's what I tell our engineering managers when they come to me with a motor request:
- If your motor is going to run at one speed for >80% of its life→ Leeson 5 HP AC. Cheaper TCO, simpler, bulletproof.
- If your motor needs to run at variable speed and you don't want to pay for a VFD→ Leeson DC motor. Better control, lower total cost in that specific scenario.
- If you're buying for a small, one-off project or a test bench→ Leeson DC. Lower entry cost (motor only), easier to interface with Arduino or PLC. Big vendors often ignore small buyers.
I've been on both sides of this decision. A few years ago, we bought a "cheaper" AC motor for an indexing conveyor, thinking we'd save money. After adding the VFD and dealing with overheating at low speed, the DC option would have been $700 cheaper overall. On the flip side, last year we bought a DC motor for a constant-speed fan application—had to replace brushes twice in 18 months (ugh). Should have gone AC.
So glad I finally built a simple TCO spreadsheet for our team. It's saved us about $8,000 in preventable motor mis-selections over the past 3 years.
Whether you're buying for a large plant or a small workshop, the key is: don't just compare the motor price. Compare the system cost—motor + drive + energy + maintenance over the life you expect to run it.
What happens when a linear actuator fails? That's a different article—but it starts with the same principle: total cost, not just the part price.
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