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Example no 1 of alarm setting:

Set the alarm of n-on type for the monitored quantity P – 3-phase active

power,

version 5 A; 3 x 230/400 V. Switching the alarm on, after exceeding 3800 W,

switching the alarm off after decreasing 3100 W.

Calculate: rated 3-phase active power: P = 3 x 230 V x 5 A = 3450 W

3450 W – 100 % 3450 W – 100 %

3800 W – ALon % 3100 W – ALoF %

It appears: ALon = 110 % ALoF = 90 %

Set: Monitored quantity: P; Kind of alarm: n-on, ALon 110, ALoF 90.0.

Example no 2 of alarm setting:

Set the alarm of earliest warning about the possibility to exceed the

ordered 1 MW power on the level 90% at the one hour accounting.

Measuring current transformer 2500/5 A, voltage :230 V, Instantaneous

maximum import of power: 1.5 MW.

Calculate: rated 3-phase active power of the ND20 meter: P = 3 x 230 V

x 2500 A (500 * 5 A) = 1.725 MW (500 * 3450 W) – 100%;

90% of ordered power / rated power = 90.0% * 1 MW / 1.725 MW = 52.1 %

of the rated meter value (rounding down).

The’ ordered hourly power (energy for consumption): 1 MWh / 4 quarters

= 900 MWs,

90% - 810 MWs. Remaining 10% at maximum power import would be

used in time: 900 MWs / 1.5 MW = 60 s

– A3_on – when the “on” alarm type occurs on any of the phases – the

relay switches on and the corresponding symbol is illuminated (AL1

– phase 1, AL2 – phase 2, AL3 – phase 3). When all alarms fade

away, the relay switches off.

– A3_of – when the “off” alarm type occurs on any of the phases –

the relay switches on and the corresponding symbol is illuminated

(AL1 – phase 1, AL2 – phase 2, AL3 – phase 3). When all alarms

fade away, the relay switches off

In the “A3” alarm series, the alarm value must range from 0-7.

They work with equal ALof and ALon hysteresis thresholds for all

of the phases. Signaling sustainment can be switched off by pressing

together and buttons (for 3 seconds).

Lumel ND20 User Manual

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