Ask any field service engineer what slows down a generator commissioning schedule and the answer is rarely the test itself. It is the logistics around the test: getting a load bank onto a truck, through a doorway, down a ramp, across a gravel yard, and into position before the generator is even started. A 500 kW skid-mounted resistive load bank is a fixed asset. A load bank that two people can lift, wheel, or split into modules is a tool you can deploy three times in one day.
That distinction is what this article is about. Below we break down what "lightweight" genuinely means in mobile testing, then profile the three load banks in our range that our own service partners reach for when a test schedule involves frequent transport, tight access, and short windows between sites.
What "Lightweight" Really Means in Field Testing
Weight on a datasheet is only the first number that matters. A load bank is light in practice when several things are true at once:
- Low weight per kilowatt. A compact resistive unit built around high-density finned elements typically lands in the 0.4–0.8 kg per kW band. Above roughly 1.5 kg per kW, you have crossed into equipment that needs lifting gear rather than a tailgate.
- Handling points designed for people, not cranes. Recessed lifting handles, balanced centre of gravity, and no sharp element guards are worth more than 5 kg of weight savings.
- Realistic power connections. Cam-lock connectors or stud terminals that accept short, manageable cable runs. If the load bank needs 4/0 cable at 20 m to reach the generator, the cable — not the bank — becomes the heavy item.
- Contained cooling airflow. Forced-air units that draw and discharge horizontally can sit close to a wall or fence. Vertical-discharge designs look compact but need clearance above, which kills placement options on a cramped site.
- Control you can put where you need it. Separating the control interface from the load enclosure — via handheld pendant, remote panel, or laptop — keeps the operator out of the hot air stream and away from live terminations.
1. RK-30 Hand-Carry Resistive Load Bank — 30 kW
The RK-30 is the unit that gets carried rather than rolled. At approximately 18 kg in its aluminium enclosure, one technician can move it from a van to a rooftop plant room without a second pair of hands, and two technicians can carry it up a stairwell in under a minute.
Key specifications
| Parameter | Value |
|---|---|
| Rated capacity | 30 kW resistive |
| Voltage | 400/480 V three-phase, 230 V single-phase |
| Load step resolution | 0.5 kW |
| Weight | approx. 18 kg |
| Enclosure | Powder-coated aluminium, IP21 |
| Cooling | Forced air, horizontal intake and discharge |
| Duty rating | Continuous at 40 °C ambient |
| Control | Front-panel toggle steps, optional 10 m pendant |
Where it earns its place. The RK-30 is aimed at the tests that do not justify a trailer: verifying a 20–30 kVA standby generator on a service visit, exercising a small UPS string, proving a marine auxiliary set, or applying a stable load during a breaker and protection relay check. Because the steps are 0.5 kW, you can follow a load profile closely on a small machine instead of slamming it from 0 to 100% and drawing conclusions from two data points.
Practical notes. Keep 300 mm of clear space at the intake grille and never less than 1 m at the discharge. The element guard is removable for inspection but should never be removed with the unit energised — the interlock on our production units drops the contactor when the panel is opened. For rooftop work, the aluminium case will get hot after a long run; allow a cool-down period before carrying it back down.
2. RM-100 Trolley-Mount Load Bank — 100 kW
The RM-100 sits in the range where a load bank stops being something you carry and becomes something you wheel. Two 125 mm braked castors and a folding handle let a single engineer move roughly 120 kg across concrete, through a standard 900 mm door, and into a plant room aisle without a pallet truck.
Key specifications
| Parameter | Value |
|---|---|
| Rated capacity | 100 kW resistive (optional 30 kVAR reactive) |
| Voltage | 400/480 V three-phase |
| Load step resolution | 1 kW |
| Weight | approx. 120 kg |
| Enclosure | Galvanised steel frame, IP23 |
| Cooling | Forced air, front intake, rear discharge |
| Control | Local panel plus 30 m remote, RS485 Modbus RTU |
| Metering | Voltage, current, kW, PF, frequency, element hours |
Where it earns its place. This is the workhorse for the 60–100 kVA band — the standby sets on commercial buildings, small data halls, telecom sites, and rental fleets. It is also the unit most of our partners choose for repetitive weekly testing, because the Modbus interface lets them script a load profile, log the run, and export a report without touching the front panel. For a service company billing by visit, that logging capability is the difference between a one-page certificate and a defensible test record.
Practical notes. The castors are rated for a 15° ramp; beyond that, use two people and a strap. The rear discharge means the unit should be positioned with its back to open space, not to a wall — a common mistake when engineers try to keep the noisy side away from the client. Cable entry is at the rear top, which keeps terminations out of the discharge plume.
3. RX-300 Modular Load Bank — 300 kW in Six Lifts
The RX-300 solves the weight problem by refusing to be one object. It consists of six 50 kW modules of approximately 26 kg each, mounted in a stacking frame or split across two transport cases. Each module is individually liftable, individually fused, and individually addressable on a shared control bus.
Key specifications
| Parameter | Value |
|---|---|
| Rated capacity | 300 kW resistive, expandable to 600 kW by paralleling two frames |
| Module capacity | 6 × 50 kW, approx. 26 kg per module |
| Voltage | 400/480 V three-phase |
| Load step resolution | 0.5 kW system-wide |
| Control | Master controller with touchscreen, Ethernet and Modbus TCP |
| Protection | Per-module over-temperature and fan-failure trip, master E-stop |
| Data | Onboard logging, CSV export, load-step ramping profiles |
Where it earns its place. Large gensets often live in places where a 300 kW monobloc load bank cannot physically go: basements with a single goods lift, offshore platforms with a deck weight limit, hospitals where the test must happen in a loading bay. Modularity also means you can take 100 kW to a small job and 300 kW to a large one using the same inventory, and a failed module can be swapped out in the field rather than pulling the whole bank from service.
Practical notes. Paralleling requires matched cable lengths and a common earth reference; unequal cable resistance will cause the modules to share unevenly under load. Ramp profiles should be stepped, not linear, when testing a generator's transient response, and the master controller's fan-failure trip should be verified before every campaign, since a blocked module fan will derate the whole string long before it trips on temperature.
Choosing Between the Three
| If your work looks like this | Choose | Why |
|---|---|---|
| Rooftop, stairwell, or one-person service visits under 30 kVA | RK-30 | Carryable, horizontal airflow, 0.5 kW steps |
| Weekly 60–100 kVA standby testing with reporting requirements | RM-100 | Single-person mobility plus Modbus logging |
| 200–600 kW gensets with access or deck-weight limits | RX-300 | Splits into 26 kg lifts, expandable, field-serviceable |
Transport and Site Practice That Protects the Equipment
- Respect ambient derating. All three units are rated continuous at 40 °C. In a plant room at 50 °C, expect to derate by roughly 10–15%; element life falls quickly above rated temperature.
- Size cable to the load, not to the connector. A 100 kW bank at 480 V draws about 120 A per phase. Undersized cable adds resistance, produces voltage drop the generator controls will chase, and turns a simple test into a fault-finding exercise.
- Never switch load on a live generator without a defined sequence. Apply load in steps, hold each step long enough for coolant temperature and voltage regulation to stabilise, and remove load in steps before shutdown. Fast removal on a large set invites overspeed and voltage overshoot.
- Check the earth path first. On mobile work, a poor earth reference is the most common cause of nuisance trips and erratic metering.
- Log element hours. Element resistance drifts with age. A unit that reads 3% low on kW at a given step is a calibration item, not a generator problem.
Maintenance for Equipment That Travels
A load bank that lives in a van takes more abuse than one that lives in a test cell. Three checks cover most of the risk. First, inspect element supports and terminal torque at every sixth deployment — vibration loosens studs. S
