Topology first, then the gap between the VA figure and the watt figure · review

DIGITUS DN-170075, line-interactive at 1500 VA and 900 W, with a runtime tied to a load in watts review

The one listing of the eight to quote its runtime against a load in watts, and the one to publish a classification code beside its topology, on a page that then says nothing about its waveform or its battery.

By Jean-Benoit Buisson

The bottom line The most completely specified page in this batch except on two lines: a runtime with its load, a classification code, both ratings, two ports and a named socket standard. The waveform and the battery are the blanks, and on a line-interactive unit the first is the one worth asking about.

On the listing

A line-interactive uninterruptible power supply rated at 1500 VA and 900 W with four earthed Schuko sockets; a reliable supply claimed for bridging short cuts and peaks and for protecting the data of a computer, a server or a video recorder; a maximum bridging time of 36 minutes at a 120 W load, with a transfer of 2 to 6 milliseconds and the capacity given again as 1500 VA and 900 W; management software for Windows, Linux and macOS that shuts a machine down in a controlled way and sends an alert by e-mail; automatic voltage regulation, boosting and bucking, under a class 2 – VI line-interactive heading; four earthed CEE 7/7 sockets for desktop machines, monitors, surveillance and till systems; an RJ45 input and output with surge protection for a router, a modem, a switch, a printer or a telephone; USB Type-B and RS232 ports with the matching cables in the box; automatic shutdown once the battery is discharged and automatic restart when the mains returns; and overload, over-discharge and overcharge protection for the batteries inside.

Thirty-six minutes at 120 watts

A time and the load it belongs to, in one sentence. This is the only place in the batch where those two arrive together. Runtime is a property of the battery and the draw taken as a pair: the pack holds a fixed amount of energy and the load decides how quickly it leaves. Quoted at 120 W, the figure can be used — add up what a machine and a monitor consume, set the total beside 120, and the direction the 36 minutes moves in is obvious. Quoted alone, as three other listings here quote theirs, it is a number about nothing in particular.

1500 volt-amperes and 900 watts

Both figures appear in the title and again in the second bullet, in the same order and with the same units. The watt rating is the smaller and it is the one a load is sized against; the volt-ampere rating is apparent power. Neither is derived from the other on the page, and neither is derived from the other here. What the page does not do is join up its own two numbers: the runtime is quoted at 120 W, well below the 900 W rating, as runtime charts generally are, and the shape of the curve between the two is not published.

Class 2 – VI, beside the words

The fourth bullet gives the topology twice over: line-interactive in words, and a code from the standard that covers these units. The code says the output is voltage-independent, which is to say the unit corrects a supply drifting within a band without moving to the battery — exactly what the boost and buck transformer in the same sentence does. Two makers can write the same topology and mean slightly different things by it; a code narrows that. No other listing in this batch prints one.

The waveform nine bullets never name

Nine bullets, and not one of them says what the output looks like on battery. That is a strange gap on a page this thorough, and it is the single line that a power supply with active power factor correction cares about. The unit regulates the incoming supply in detail and describes that regulation at length; what it produces once the mains goes away is not described at all.

Before ordering

Ask for the waveform and for the size of the battery. Everything else here is stated — topology, classification, both ratings, a runtime with its load, two ports and their cables — and the battery is the part that will need reordering first.

Availability

Priced from 160 € to 211 € across the German, French, Italian and Spanish Amazon stores the day this page was checked.

It is stocked on the British Amazon store as well, in that country’s own currency. The range above leaves those out: it counts euro stores and no others.

In the American Amazon catalogue with no live offer against it: the reference exists, nobody is filling it.

Every figure in this section is what Keepa held on the day this page was last updated. Stock and prices move without warning.

Prices quoted in this text were read on 10 September 2026. The live price is at the top of the page.

Where it holds up, and where it stops

Strengths

The runtime is published against a load in watts, which is the only form in which such a figure can be checked before buying
A classification code is published beside the topology, so the arrangement is stated twice and in two vocabularies
Two communication ports are named, their cables are counted and the operating systems the software runs on are listed

Compromises

No waveform anywhere across nine bullets, on a unit whose regulation is described at length
The battery is protected in three named ways and described in none, so there is nothing to reorder against
Nothing says which of the four sockets keep working once the mains fails

Specifications

Topology	Line-interactive — named in the second and fourth bullets, with automatic voltage regulation that steps a low or high supply up or down through a transformer instead of calling on the battery
Stated classification	Class 2 – VI — stated in the fourth bullet beside the topology. The code names a voltage-independent arrangement under the standard that covers these units, and it is the only classification published in this batch
VA rating	1500 VA — printed in the title and repeated in the second bullet as one half of the stated capacity
Watt rating	900 W — printed in the title and repeated in the second bullet. It is published as its own quantity rather than folded into the rating beside it, and it is the figure a connected load is added up against
Stated runtime at a named load	Up to 36 minutes at a 120 W load — stated in the second bullet, which gives the time and the load in the same sentence. It is the only runtime in this batch published against a figure in watts, and it is therefore the only one that can be checked against real equipment
Output waveform	Not published on the listing — nine bullets describe the regulation, the software, the sockets, the ports and the protections, and none says whether the output on battery is a sine wave or a stepped approximation
Socket count	Four — printed in the title and counted again in the fifth bullet
Socket type	Schuko, given as CEE 7/7 — stated in the fifth bullet, which names the standard rather than the trade name alone. Which of the four stay live on battery is not said
Battery type	Not published on the listing — the ninth bullet names overload, over-discharge and overcharge protection for the batteries inside and never gives their voltage, their capacity, their count or their chemistry
Battery replaceability	Not published on the listing — the batteries are described as built in and nothing says whether the pack is reached by the owner
Communication port	USB Type-B and RS232 — stated in the seventh bullet, which adds that the matching cables are in the box. The third bullet names software for Windows, Linux and macOS that shuts a machine down in a controlled way and sends an alert by e-mail
Amazon reference	B07GQBPPN3 (same reference on 6 Amazon marketplaces)
EAN	4016032441373

The questions that come up before an order

Why does 36 minutes need the 120 W beside it?

Because runtime is not a property of the unit on its own. The battery holds a fixed amount of energy, and how long it lasts depends entirely on how fast the load draws it out. A figure of 36 minutes at 120 W says something checkable: add up the consumption of what will be plugged in, and if the total exceeds 120 W the time falls, steeply. The same figure printed alone says nothing at all, and three of the four runtimes in this batch are printed that way.

What is a classification code doing on a UPS?

Describing the arrangement in a fixed vocabulary rather than in marketing words. The standard for these units classifies them by how the output behaves relative to the input, and a voltage-independent unit corrects a supply that drifts within a band without moving to the battery. Two makers can both write line-interactive and arrange the inside differently; a code narrows what the words mean. One listing in this batch prints one.