Brainboxes PX-246 Especificaciones descargar pdf (Pagina 11)

Specification

3.5.2 CT POLARITY

Take care to ensure the correct polarity of the CTs. Incorrect CT orientation will lead to negative kW

readings when the set is supplying power. Take note that paper stick-on labels on CTs that show the

orientation are often incorrectly placed on the CT (!). It is more reliable to use the labelling in the case

moulding as an indicator to orientation (if available).

To test orientation, place S1/S2 on load to around 10% of their rating. Ensure the DSE module shows

positive kW for all three individual phase readings.

TO S1 or S2

TO LOAD SWITCH DEVICE

POLARITY OF CT PRIMARY

NOTE

NOTENOTE

NOTE:

: :

: Take care to ensure correct

Take care to ensure correctTake care to ensure correct

Take care to ensure correct

polarity of the CT primary as shown above. If in

polarity of the CT primary as shown above. If in polarity of the CT primary as shown above. If in

polarity of the CT primary as shown above. If in

doubt, check with the CT supplier.

doubt, check with the CT supplier.doubt, check with the CT supplier.

doubt, check with the CT supplier.

3.5.3 CT PHASING

Take particular care that the CTs are connected to the correct phases. For instance, ensure that the

CT on phase 1 is connected to the terminal on the DSE module intended for connection to the CT for

phase 1.

Additionally ensure that the voltage sensing for phase 1 is actually connected to S1/S2r phase 1.

Incorrect connection of the phases as described above will result in incorrect power factor (pf)

measurements, which in turn results in incorrect kW measurements.

One way to check for this is to make use of a single-phase load. Place the load on each phase in turn

of S1/S1 and ensure the kW value appears in the correct phase. For instance if the load is connected

to phase 3, ensure the kW figure appears in phase 3 display and not in the display for phase 1 or 2.

3.5.4 CT CLASS

Ensure the correct CT type is chosen. For instance if the DSE module is providing overcurrent

protection, ensure the CT is capable of measuring the overload level you wish to protect against, and

at the accuracy level you require.

For instance, this may mean fitting a protection class CT (P10 type) to maintain high accuracy while

the CT is measuring overload currents.

Conversely, if the DSE module is using the CT for instrumentation only (current protection is disabled

or not fitted to the controller), then measurement class CTs can be used. Again, bear in mind the

accuracy you require. The DSE module is accurate to better than 1% of the full-scale current reading.

To maintain this accuracy you should fit Class 0.5 or Class 1 CTs.

You should check with your CT manufacturer for further advice on selecting your CTs

labelled as p1,

or K

labelled as p2,

or L

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Brainboxes PX-246 Especificaciones Pagina 11

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