SDMO Generator Procurement Checklist: 8 Steps I Use Before Every PO

This checklist is for procurement and facilities managers evaluating 20–1250 kVA industrial diesel generators — specifically SDMO and Kohler-SDMO units. Eight steps, in order. Follow them and you'll avoid the four overspend traps that cost us roughly $11,200 across two budget cycles.

When I first started buying generators, I assumed the lowest quote at the same kVA rating was the same product. Three repair bills and one 14-hour outage later, I learned the difference between a spec sheet and a deployment.

Here's the checklist I actually run now.

Step 1 — Fix your unit before you look at a single quote

A 60 kW SDMO diesel generator and a 60 kVA unit are not the same thing. At the standard 0.8 power factor, 60 kW is rated at roughly 75 kVA. An 800 kVA SDMO generator delivers around 640 kW. Vendors quote in whichever unit makes their number look better. If you don't lock the unit first, you're comparing apples to a spreadsheet that says "apple."

Write your load requirement in both kW and kVA, put it in the RFQ, and require each vendor to confirm which unit they're quoting in writing. This alone killed a 9% "savings" on our last bid round — turned out it was a unit mismatch, not a discount.

Step 2 — Decide if inverter technology fits your load, before you compare models

If you've ever wondered what is an inverter generator and whether it matters at industrial scale, here's the short version: an inverter unit converts AC to DC and back to AC, which produces a cleaner waveform and allows variable engine speed. Conventional units run at fixed RPM and produce a waveform tied to engine speed.

For most industrial backup loads — motors, HVAC, pumps, plant lighting — conventional is fine and cheaper to service. Inverter units earn their premium when you're feeding sensitive electronics, telecom gear, or mixed loads where frequency stability actually matters.

Don't let a rep sell you inverter tech for a load that doesn't need it. And don't let a conventional unit get spec'd for a load that does. Get your electrical engineer to confirm which side of that line your facility sits on before the RFQ goes out. This is the step most people skip (note to self: I skipped it twice in 2022).

Step 3 — Confirm the factory dispatch: SDMO or Kohler-SDMO

Both exist in the market, and the distinction matters for parts availability and service coverage. Kohler-SDMO branded units follow Kohler's distribution and warranty framework; legacy SDMO units route through the older network. Ask the vendor to state, in writing, which dispatch path your specific unit will follow. Then call the nearest authorized service center and confirm they stock parts for that specific model year.

I once signed a PO for what the quote described as a "Kohler-SDMO generator" and later found out the service network treated it as legacy SDMO. Nothing wrong with the machine — but the first-year-filter price difference was 40% more than the Kohler-part route we'd budgeted for.

Step 4 — Size your solar/battery fit before you commit the diesel spec

A Titan solar generator or a comparable battery-based portable unit isn't a replacement for industrial diesel backup. But it can absorb a narrow slice of your critical load — controls, comms, monitoring — which lets you downsize the diesel unit you need to buy and run.

For our facility, pulling the SCADA and monitoring load onto battery backup dropped the genset we needed from 100 kVA to 75 kVA. That was a ~$14,000 procurement savings and roughly $900 per year in no-load fuel burn we no longer pay for. Not a dramatic win, but real.

Check the battery's runtime curve against your critical load — not the marketing number on the box. Most of these units claim a runtime based on a fraction of the load you'll actually put on them.

Step 5 — Audit the small components. Especially the electric fuel pump relay kit.

This is the step most checklists miss. A fuel pump relay kit runs $40–$90. When it fails, you don't get a warning light — you get a genset that cranks and won't start.

Ask every vendor three questions: (1) what's the part number for the fuel pump relay on this specific model, (2) do you stock it locally, and (3) what's the replacement interval your factory actually recommends — not the sales brochure. Then buy a spare. We keep one on the shelf for each of our three units. It's the cheapest insurance in your entire procurement.

Same audit applies to battery chargers, coolant sensors, and starter solenoids. Each is under $200. Each takes the whole unit offline when it fails. Budget $500 per genset to stock the top failure points.

Step 6 — Build the 5-year TCO, not the purchase price comparison

Here's where a spreadsheet beats intuition. The purchase price of an 800 kVA unit is often only ~35–45% of the total 5-year cost. Fuel, annual service, load-bank testing, oil and filter intervals, and downtime carry the rest.

Build your model with these line items:

• Purchase + freight + rigging
• Switchgear and installation (often 25–40% of the genset itself)
• Annual service contract (per kVA, per hour, or per visit — read the fine print)
• Load bank testing (annual for standby units in most jurisdictions)
• Fuel at assumed run hours × local diesel price, with a 5–8% annual fuel inflation assumption
• Expected downtime cost at your facility's $/hour of outage

Reference standard: ISO 8528 is the governing standard for generator set performance classes and duty ratings — make sure your vendor is quoting against a specific class, not just "industrial grade."

Step 7 — Get service coverage in writing with response-time SLA

"Certified service partner network" is a marketing phrase. Ask for the specific nearest authorized center, the actual response-time commitment, and the escalation path if the first technician can't resolve the issue.

On one bid round, the spreadsheet said go with the vendor that was 12% cheaper. My gut said stick with our existing supplier. I went with the spreadsheet. Turns out the cheaper vendor's "national service network" was one technician and a van, three hours away. When a 400 kVA unit tripped on a winter morning, we spent 6 hours on a phone chain. That 12% savings was gone by lunch.

Now I require: named service center, written response-time commitment, parts-availability guarantee, and a reference customer of similar size in similar geography. All in the PO, not the brochure.

Step 8 — Read the warranty exclusions line by line

Warranties on industrial diesel gensets typically exclude: damage from incorrect fuel, improper storage before commissioning, unauthorized field modifications, and "consequential damages" — which is the phrase that swallows your real losses.

Ask for the full warranty document, not the summary. Then have your legal contact mark every exclusion that applies to your operating environment. On an agricultural processing site with variable fuel quality, the fuel-exclusion clause alone can void most of the warranty if it isn't negotiated.

Common mistakes I've made so you don't have to

Assuming 60 kW models are interchangeable. They aren't. Two units at identical nameplate ratings can have very different alternator quality, enclosure ratings, and control panel configurations. The alternator in particular determines your real usable load.

Skipping the fuel pump relay kit audit. It's boring. Do it anyway. A $60 part failing at 2 a.m. costs more than the entire relay assembly you could have stocked.

Comparing purchase price instead of TCO. This is the single biggest procurement error on industrial gensets. Purchase price is a minority of the cost.

Believing the "100% maintenance-free" pitch. No diesel generator is. Any vendor who says otherwise is either new or selling a different product.

Forgetting power factor when comparing specs. An 800 kVA unit at 0.8 pf and an "800 kVA" unit at 0.9 pf are different machines. Ask for the kW rating at the pf you'll actually run at.

Prices and lead times referenced here are based on our procurement records through Q3 2024 — verify current pricing before you commit. Service standards, warranty terms, and factory dispatch routes are best confirmed directly with the vendor's written documentation.

Rebecca Sloan

Rebecca Sloan is a power distribution and protection analyst specializing in circuit breakers, switchgear, contactors, fuses, surge protective devices, and coordination. She applies IEC 60947-2 breaker requirements, IEC 60269 fuse characteristics, and IEC 61643-11 tests while examining rated voltage, breaking capacity, time-current curves, selectivity, and prospective short-circuit current. She helps engineers and buyers compare protective devices against documented fault levels, installation conditions, maintenance access, and continuity priorities.