Facility systems: a big generator and telemetry of everything

Research note, October 27, 2026, by Alexander Grabowski (B4L). Sources were retrieved on October 27, 2026. Figures are cited, and our own estimates are marked.

This note covers the backup generator plant and the telemetry of everything in and around the option B data center, which the investor would build, own, and run. The design basis and the sites are in option B and in site selection. Money is given in THB, with USD in parentheses at 33 THB per USD, the B4L planning rate.

In short

• BOI's conditions for data centers ask for "an engine generator system with a continuous rating that supports the total power load of the data center", a backup if any set fails, and concurrent maintainability.[389] Standby-rated sets, as at least one Thai assembler lists them, do not meet that wording (our reading).[667]
• For 1.2 to 2.4 MW of total load, three continuous-rated sets of 1,600 to 1,875 kVA, one of them spare, carry the full build, and two carry phase 1. At a trade estimate of USD 450 to 600 (15,000 to 20,000 THB) per kW installed, the full plant costs about 57 to 89 million THB (USD 1.7 to 2.7 million) (our estimate).[668]
• Up to 15,000 L of diesel needs only a notification, more needs a DOEB license, and a tank of up to 2,500 L built into each emergency generator does not count toward the total.[669][670][671] DOEB has suspended new permits for emergency fuel tanks at data centers (news, September 2026).[393] Three built-in tanks plus 15,000 L in bulk give about 36 hours at 2.4 MW and 72 hours at 1.2 MW (our calculation, to be confirmed with DOEB).
• PEA's 2024 averages are about 1.2 interruptions and 21 minutes per customer in both the North and the Northeast, against the regulator's limits of 3.25 interruptions and 76.87 minutes.[672][672] Power still causes 45% of impactful data-center outages, most often through the UPS.[253]
• The load swings of GPU training stress generators more than anything else. In a Vertiv test, 20% input smoothing at the UPS cut the swings in generator voltage and frequency from about ±10% to ±0.5%.[673][674]
• ASHRAE allows 70% humidity in the hall only if copper and silver coupons corrode by less than 300 and 200 Å a month; otherwise the limit is 50%.[636] Northern haze carries sulfate and nitrate salts, so corrosion should be measured (our judgment).[675]
• Most outside risks have free data feeds (Air4Thai, TMD, ThaiWater, NASA FIRMS, and USGS), but grid outages and lightning do not.[676][677][678] The sensors we could price for a 1 MW hall cost about 0.75 million THB (USD 23,000); smoke detection, meters, and integration need quotes (our estimate).

Backup power: what the rules ask for

The BOI wording is that a project "must have an engine generator system with a continuous rating that supports the total power load of the data center, and a backup system to ensure continuous operation in case any engine generator fails or ceases to function", and that it "must be able to service clients during maintenance or equipment replacement in the system (concurrently maintainable)".[389] Read plainly, that means N+1 continuous-rated sets sized for the whole facility, cooling included (our reading).

Uptime's premise is that the engine-generator plant is the only reliable source of power, so only continuous, derated prime, or unlimited-runtime standby ratings qualify for Tier III and IV.[682] Two 24-hour tanks count as 24 hours of Tier III fuel, not 48, and a gas line counts as a utility, so a plant that runs on gas must still store 12 hours of fuel on site.[680][680]

The rating label is a trap. Cummins says that the ISO 8528-1 data center power (DCP) rating "is not appropriate" for Tier III or IV, because it refers to a reliable utility and prohibits prolonged parallel operation.[683] MTU sells its 12V4000 DS1650 under a "data center continuous power (DCP)" rating that, it says, complies with Tier III and IV.[684] Both are interested vendors. Uptime accepts a manufacturer's letter stating that a set has no limit on run time at a given rating and site, so we would require that letter whatever the label says (our judgment).[683]

Thai rules are changing. Data centers are to become a building category of their own, in five size classes, with rules on "backup fuel storage tanks for emergency power systems", and Reuters reports seven tiers by power demand.[685][497] The two may be different sets of rules; either way, the rules on fuel are tightening (our reading).

Sizing the generator plant

The load is 1 to 2 MW of IT times a PUE of about 1.2, or 1.2 to 2.4 MW, plus UPS recharge and growth (our arithmetic).

The capacities take a power factor of 0.8 where only kVA is given, and the MTU set leaves little room for growth. Phase 1 (1.2 MW) needs two large sets: one runs at about 94% while the other is serviced, or both run at about 47% (our arithmetic). Cummins advises keeping diesels above 30% load to avoid wet stacking and notes that real data centers often run at 36 to 39%, so a phased build should not install every set on day one.[683]

Low or medium voltage is still an open choice. At 400 V, one 1,600 kVA set carries about 2,300 A, so three in parallel put about 7,000 A on the bus (our sum), and MTU and Mitsubishi also build 11 kV versions.[684][687] Both should be priced; we found no source on the usual switch-over point. The first data center splits the sets between two yards, one for each power path, so each switchboard's generator section carries at most two sets, about 4,600 A, and the bus tie between the boards runs the two sections in parallel (our sum).

The table uses 0.26 L per kWh (our estimate). MTU's sheet gives 323.3 L/h at 1,280 kW (0.25 L/kWh), rising to 0.27 at half load, and a Cat 3512B burns 308.8 L/h at 1,200 kW.[684][688] Real loads below nameplate stretch these hours.

GPU load swings. Uptime reports GB200 NVL72 racks jumping from about 60 to 70 kW to over 150 kW, and calls generators "the most stressed" equipment under such swings.[673][673] In a Vertiv test with STT GDC and Baudouin, frequency swings on generator power blocked UPS bypass synchronization once the AI load passed about 75% of IT capacity, and 20% battery input smoothing at the UPS cut the swings from about ±10% to ±0.5% (vendor test).[674][674] NVIDIA says the GB300 NVL72 power shelf cuts peak demand by up to 30% with stored energy and a gradual ramp-down (vendor claim).[689] We would specify three things (our judgment): ISO 8528-5 class G3 with 100% one-step load acceptance shown at the factory test, as MTU and Kohler state for their sets; input power smoothing at the UPS; and GPU power smoothing switched on.[684][690][673] Caterpillar warns that a custom load step written into a G3 specification turns it into class G4, which needs the maker's agreement.[691]

Cost. A trade estimate puts large diesel sets installed, with enclosures, exhaust, paralleling switchgear, and commissioning, at USD 450 to 600 per kW, up from USD 380 to 420 in 2023, with lead times of 18 to 24 months for units above 2.5 MW (ours are smaller).[668][668] For 3,840 kW (3 x 1,280 kW) to 4,500 kW (3 x 1,500 kW) installed, that comes to about 57 to 89 million THB (USD 1.7 to 2.7 million), and the two MTU-size sets of phase 1 cost 38 to 51 million THB (USD 1.2 to 1.5 million); tanks, medium-voltage switchgear, and the building come on top (our estimates). The plant is thus roughly 6 to 14% of option B's 640 million to 1.02 billion THB for 2 MW. Thai prices for the sets alone are lower. A Thai dealer lists a new silent 500 kVA set at 1.5 to 2.5 million THB, about 3,750 to 6,250 THB per kW (our arithmetic), and a Udon Thani public-health reference price is 5.35 million THB for a set of at least 800 kW (search result only, not verified).[692][693] At 4,000 to 7,000 THB per kW, three MTU-size sets alone would cost 15 to 27 million THB; switchgear, enclosures, exhaust, commissioning, and the US price level make up the gap (our reading). We found no Thai quote for continuous-rated sets of 1,500 to 2,000 kVA.

Two reference points. Hetzner, the German host that serves as this study's benchmark, gives each data-center unit N+1 UPS, one 2.5 MVA diesel generator, and two power paths from the substation.[487] A press visit found that only busbar A was backed by UPS, that the generators were serviced monthly and run under the full hall load once a year, and that each generator had 30,000 L of fuel for three to four days.[488][488] That is a lean design with no Tier claim (our reading; see business hosting). CMU ITSC, where the investor's first servers would be hosted under option A, runs its whole room on backup systems of 120 and 125 kVA and one 320 kVA generator.[15] The plant above has ten to fifteen times that capacity.

The noise of the generator plant, during monthly tests, yearly full-load runs and a grid outage, is assessed against the Thai rules and lender benchmarks in noise.

Fuel: permits, storage, and quality

Under the Fuel Control Act B.E. 2542, diesel is a low-flammability fuel. A storage place for more than 454 L and up to 15,000 L is Category 2, and its owner notifies DOEB first; more than 15,000 L is Category 3, which needs a DOEB license before any fuel is stored, up to 500,000 L in total.[669][669][670] The 2024 Ministerial Regulation on oil storage places does not count as an "oil container" a tank of up to 2,500 L per emergency generator built in under the Engineering Institute of Thailand standard, and Category 3 tanks that feed generators need leak detection and alarms.[671][671]

On September 2, 2026, The Nation quoted the energy minister's secretary as saying that the Department of Energy Business "had suspended the issuance of new permits for emergency fuel tanks at data centres" while standards are drafted; one Bangkok data center is licensed for 200,000 L.[393][393] This is news only. We found no DOEB notice, and whether Category 2 notifications are caught is unknown.

Uptime's 12 hours, and 48 hours in phase 1, therefore fit without a Category 3 license, but 48 hours at full build does not. We would lay out the tank farms for a later license and sign a refueling contract (our judgment). In hot weather, fuel returning from the engine can overheat the day tank and derate or trip the set; Uptime's remedies are recirculation to an underground bulk tank or a fuel cooler.[680]

Other permits. Any generating source of 200 kVA or more needs a Phor Kor 2 controlled-energy license, applied for at DEDE for standby plant, but emergency-only own use is not an energy business, so no ERC license is needed.[694][694] An EIA starts at thermal plants of 10 MW, far above this plant (our reading of a consultancy's list).[695] Two rules are pending: the building category above, and a draft ERC license for selling power to data centers that would ask for the site's backup-power plan, storage, load profile, and continuity plan (secondary source).[696]

Fuel quality. Thai diesel moved from B5 to B7 in March 2026 and stayed at B7 at least until September 13.[697][698] Biodiesel ages in storage, and testing burns little of it. Monthly 30-minute runs at 30% load on three sets, plus a yearly one-hour test at full load, use about 3,200 L a year (36 x 0.5 h x 384 kW at about 0.33 L/kWh, plus 3 x 323 L), so 22,500 L turns over only every seven years (our estimate). The fuel therefore needs polishing, which Uptime counts as an operations practice.[680] At a US vendor's USD 0.16 to 0.70 per gallon, one polish of 22,500 L costs about 31,000 to 137,000 THB (USD 950 to 4,200) (our arithmetic).[699]

HVO. Hydrotreated vegetable oil (HVO), a renewable diesel, is approved for the MTU and Kohler sets, with up to 4% more fuel by volume on the Kohler.[684][690] Thailand's first domestic HVO was 1,000 L from Bangchak for shuttle vehicles at a 2026 KMITL expo, a demonstration.[700] MTU puts HVO at 2 to 3 times the price of fossil diesel.[701] We would specify HVO-approved engines and switch when Thai supply exists (our judgment).

Alternatives and complements

Natural gas. PTT's provincial pipeline reaches Nakhon Ratchasima: about 120 km of 28-inch pipe along Highway 2 from Saraburi.[702] We found no pipeline reaching Chaiyaphum or Chiang Mai. Bi-fuel conversions start on diesel, run on up to 60 to 70% gas, and can still run on diesel alone.[703] Uptime counts the gas line as a utility, so the 12 hours of stored diesel are still needed.[680]

Rotary UPS. A diesel rotary UPS (DRUPS) joins a generator, a kinetic energy store, and a diesel engine in one machine.[704] A trade estimate puts it at USD 400 to 600 (13,000 to 20,000 THB) per kW installed, against USD 150 to 250 (5,000 to 8,000 THB) for a static UPS.[668] Hitec claims up to 97% efficiency, 40 to 60% less space, and no batteries (vendor claims).[705] A DRUPS could replace both the UPS and the generators, but it fits poorly with the solar and battery plan (our judgment).

Batteries. Microsoft's batteries bridge the roughly 30 seconds until its generators start; at its Swedish site, Saft built four 4 MWh groups that give up to 80 minutes of backup in place of diesel.[706][707] For UPS batteries, lithium iron phosphate costs USD 300 to 400 (10,000 to 13,000 THB) per kWh and lasts 10 to 15 years, against USD 120 to 150 (4,000 to 5,000 THB) and 3 to 5 years for lead-acid (trade estimate).[668] The battery in site selection (10 to 20 MWh per MW of IT) shifts solar power into the night. Holding 2 MWh of it in reserve would carry 2.4 MW for about 50 minutes, or 1.2 MW for about 100, if its inverters can run the site as an island (our arithmetic and judgment). That reserve rides through most interruptions and absorbs GPU swings, but it does not replace the generators that BOI requires.

Hydrogen. Microsoft and Plug Power demonstrated a 3 MW hydrogen fuel-cell backup in 2022 (vendor claim).[708] With no hydrogen supply found in Thailand, it is not practical today (our reading).

Our recommendation (judgment). The investor should buy continuous-rated diesel sets in an N+1 arrangement, approved for HVO and backed by an OEM letter on unlimited hours. The UPS should have input power smoothing and lithium batteries, and the solar battery should be sized to double as ride-through. Gas bi-fuel makes sense only at a Korat site near the PTT pipeline. We would use neither DRUPS nor hydrogen.

How often the grid fails

The averages leave out the three southernmost provinces and events caused by severe accidents, force majeure, catastrophes, and severe generation failures.[709] Big events fall outside them. On May 21, 2013, 14 southern provinces went dark when one 500 kV line was down for maintenance and lightning tripped the other.[710] Our reading is that the investor should expect one or two sustained interruptions a year, plus dips that the UPS rides through, so most generator hours will be tests. A second feed helps, but under EN 50600 a second feed from the same grid is not a secondary supply, and the generators must still be able to replace both.[711]

The weak point is the backup chain. Power caused 45% of the most recent impactful outages in Uptime's 2025 survey, most often through UPS issues, and many outages happen when a UPS or generator fails to respond to a disruption of the grid.[253][712] Testing is the cure; the table lists the usual practices.

On USD 1.7 to 2.7 million of plant, a full-service contract costs about 0.9 to 2.2 million THB (USD 26,000 to 68,000) a year (our estimate). Testing on the real IT load, with the UPS in double conversion as Vertiv advises, saves hiring a load bank (our judgment).[674]

Telemetry: what has to be measured

Nearly 40% of organizations had a major outage caused by human error in three years, and 85% of those came from procedures that were flawed or not followed.[484] Tier III concurrent maintainability extends to plant controls, generator start, and emergency power-off, so the monitoring needs A and B paths too (our reading).[716]

All the rows come from ASHRAE's 2021 thermal guidelines.[636][636][636] Because of the 15-minute limit, inlet sensors should log every one to five minutes (our judgment).[636] Liquid-cooled GPUs still send about a tenth of their heat to the air (see option B), so these limits apply to the hall too.

Contamination. ASHRAE asks for a hall clean to ISO 14644-1 Class 8, with room air filtered at MERV 8 and incoming air at MERV 11 or 13.[717][717] It sets copper corrosion below 300 and silver below 200 Å a month (ISA-71.04 level G1), with gas-phase filtration where a site misses G1.[717][717][717] As a rule it keeps humidity below 60%, because dust that turns wet at low humidity corrodes, and it recommends real-time corrosion monitoring with outside-air economizers or gas-phase filters.[717][717][717] Coupons hang for 30 days and then go to a lab. LBNL found readings in one data center that differed by a factor of two or more, and copper coupons miss chlorine, so silver ones are added.[717][718][718] Storage drives are corrosion's foremost victims, Uptime notes.[719]

Thai corrosion risk. CMU sampling in the 2019 burning season found aged northern haze dominated by ammonium sulfate and potassium nitrate, and fresh smoke near Chiang Dao carrying potassium chloride.[675][720] These salts take up water, which makes them the corrosive dust that ASHRAE warns of (our reading). The North had 129 days above the PM2.5 standard in 2024, and the Northeast 113.[321] Near Mae Moh, a 1990s study held by the US EPA found SO2 fumigation almost daily in the cool season, with one-hour averages commonly at 1,000 to 2,000 µg/m³.[721][721] A facility can also be its own source. On September 3, 2026, the Pollution Control Department found hydrogen sulfide and oil-related VOCs at around 3 ppm in water samples at a Bangkok data center after complaints about odor (news).[722] Measurements should therefore cover the fuel farms and the drains too (our judgment).

All the prices in this table come from one reseller's catalog.[723]

Outside: free data feeds and their gaps

A station on site fills the gaps (our judgment). It would measure the weather, particles at the air intake, SO2, and H2S, and it would carry a lightning detector or use a paid lightning feed, since we found no free feed that allows commercial use. It would also have a seismic switch, which matters most in Chiang Mai's seismic Zone 3.[314]

B4L's experience. B4L, the consultant, runs a public river-monitoring service (water.buildfor.life) that ingests live gauge feeds from the Royal Irrigation Department and ThaiWater every hour, with dashboards, flood forecasts, and alerts. One lesson carries over: the irrigation feed publishes nothing overnight and sends the night's readings in one morning batch, so an alert must never read silence as calm. This is B4L's own service and not part of the investor's facility.

Inside: sensors and meters

The plan assumes a 1 MW hall of about 20 racks: 7 liquid-cooled GPU racks and 13 racks for network, storage, and hosting (our assumption, after option B and business hosting).

The SEN55 reads humidity only to 4.5% RH, so it cannot hold a 50% limit; the Vaisala probes do that job, and the cheap nodes map particles.[737] On the liquid loops, OCP's PG25 guideline (revision 2.0, Sep 15, 2026) wants in-line monitoring wired to the building management system for automatic alerts and glycol above 25% against microbes, and it warns that pH probes drift and foul in glycol.[743][743][743] ASHRAE flags trapped air in the coolant as a cause of cavitation and corrosion.[747]

Metering. Thailand has no reporting rule like the EU's, but EU Delegated Regulation 2024/1364 makes a ready minimum log. It asks for total energy at every supply before the transfer switchgear, with generator energy "measured separately", IT energy at every UPS output, water input, average waste-heat temperature, and the IT intake setpoint.[748][748][748] The Green Grid's PUE Level 3 measures IT energy at the equipment input, continuously at intervals of 15 minutes or less, and collects it automatically.[749][749] We would build to both from day one. With no outage feed from PEA, the Class A meters become the record of every dip (our judgment).

Architecture. Sensors and controllers speak Modbus, BACnet (an ISO standard), SNMP, or Redfish.[750] Two collectors (A and B) on a separate operational-technology network poll them into a time-series store that feeds dashboards and alerts linked to runbooks. Smoke detection, suppression release, and generator auto-start stay on their certified controllers, which the monitoring observes but does not control (our judgment). The software is described in the open infrastructure note.

The unpriced items, and integration above all, will dominate this budget (our judgment).

What this means for the investor

What follows is our judgment.

The big generator should be budgeted as a plant. Three continuous-rated sets of 1,600 to 1,875 kVA (2+1) cost about 57 to 89 million THB installed at full build and 38 to 51 million THB for phase 1, with an OEM letter on unlimited hours. Standby-rated sets fail the BOI wording.

The fuel system should be designed to the permits. About 22,500 L (36 hours at full load, 72 at half load) fits a Category 2 notification if the built-in tanks do not count, while 48 hours at full build needs a Category 3 license, which is now suspended for data centers. An answer from DOEB should be an early milestone.

The GPUs should be made gentle on the generators, with UPS input smoothing, GPU power smoothing, and a 100% load step tested at the factory.

The solar battery should serve twice, for ride-through as well as for shifting solar power. Gas bi-fuel makes sense only at a Korat site near the pipeline.

Corrosion should be measured before the air side is designed. Coupons at the chosen site, through one dry season and one haze season, will decide whether 70% humidity is allowed or gas filtration is needed.

Telemetry should run from day one. EU-style meters and PUE Level 3 prove BOI's PUE condition, and the outside feeds are free, but grid events, lightning, and gases need sensors on site.

Open questions