# What do the flashing rates on an Elster REX2 electric meter signify?

Our electric service (USA) is metered with an Elster REX2 digital smart meter. There is a main display area that cycles through some lines of information, most importantly the total energy used. Below the main display is a double-headed arrow made of three elements (it looks something like ◀︎ ■ ▶︎). The arrow flashes slowly or quickly to indicate direction and rate of energy flow—the arrowhead flashes on and off relatively quickly, and the central box flashes less often.

I’m wondering what exactly those flashes indicate. Is the arrowhead one watt and the central box ten? Or is it ten and fifty? Fifty and 200?

Home Improvement Asked on November 12, 2021

From the technical manual for the A3 ALPHA, a similar Elster meter:

The real energy indicators blink at a rate proportional to kWh consumption. The center square indicator will blink to indicate pulses of Kh. Each square indicator pulse (turns on and off) indicates 1 Kh. A single transition (on–to–off or off–to–on) indicates 1⁄2 Kh. The left and right arrows blink at a faster rate representing Ke. Each arrow pulse (turns on and off) indicates 1/12 Kh energy measurement. This means that a single transition of an arrow pulse (off–to–on, or on–to–off) represents 1/24 Kh. The left and right arrows indicate energy being either received or delivered, respectively.

Kh should be printed on the front of the meter; on mine, it's 7.2.

So each on-off-on cycle of the right arrow of my meter means my house used (7.2 Wh)/12 = 0.6 Wh of energy, and each on-off-on cycle of the square means 7.2 Wh.

To measure current power, you'd take a stopwatch and time one of those transitions. e.g. I just measured 20 seconds for half a cycle of the square, so that's

7.6/2 Wh × (3600 sec/hr ÷ 20 sec)
= 3.6 Wh × 180 h–1
= 648 watts.

Answered by user1539692 on November 12, 2021

According to the manual the arrow box arrow are real energy indicators Of 3.2 Rex meter tech manual

They pulse at a rate proportional to the rate of consumption. Each square pulse indicates 1kh. each change of state on to off indicates 1/2kh.

The arrow toggles for each Ke Left arrow energy received Right arrow indicates energy delivered. It said see table 2-1 for ke values per meter form. Form 1s, 2s, 12s. ke.1 kh1.0 Form 3s, 4s ke. 0.01 HK 1.0

So it depends on the meter form The different forms are the class meter 20, 200, 320 2 wire or 3 wire single phase and if there is a disconnect link.

Answered by Ed Beal on November 12, 2021

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