Using ESS030W-1750-14-Z1 as an example part number:
The datasheet doesn’t spell out the first three segments, but they follow a consistent pattern across the series. “ESS030W” is the series and power class: ESS is the standard case, ESST is the thermally enhanced case used only on the 40 W model, and the number is the top of the power band, so this one is the 21-30 W class. “1750” is the output current in mA, so 1750 mA. “14” is the maximum output voltage in Vdc, so 14 V max. The optional “-Z1” at the end means a non-linear 0-10 V dimming profile with dim-to-off, instead of the default linear profile.
Max output power is roughly the current times the max voltage, so this driver works out to about 24.5 W (1.75 A × 14 V).
Power class prefixes:
ESS010W: up to 10 W
ESS015W: 11-15 W
ESS020W: 16-20 W
ESS030W: 21-30 W
ESST040W: 31-40 W
Optional suffixes:
-Z1: 10 V to 8.1 V is 100%, 1 V to 0.8 V is 1%, and the driver turns off below 0.8 V. It needs a small plastic dongle outside the driver case, and the datasheet recommends it for standard in-wall logarithmic 0-10 V dimmers.
-Y1: Also non-linear with dim-to-off: 10 V to 9.1 V is 100%, 1.2 V to 0.6 V is 1%, and off below 0.68 V. The datasheet describes it in the dimming section, but no -Y1 models are listed for ordering.
-XL: Extended 12 in (300 mm) leads. The standard leads are 152 mm (6 in) long.
Without a suffix, the driver uses the default linear 0-10 V profile, where 10 V is 100% of output current and 1 V is 10%