ABB SPAJ 140c relay ... plz help

for a start it would help if you typed in english and not "SMS speak" and second you need to give a bit more info if you want help, because quite frankly I don't understand what you want. However I have enclosed some details on CT's for you. It is applied in submersible pumps, but a CT is a CT hope it helps.[p/]

7.2.2 Current Transformers Electronic and mechanical measuring devices monitor the amperage in the switchboard. To monitor the motor current, it must be reduced to a level that is easier to measure. If the amperage drawn by the motor was not reduced, measuring devices would have to be large and cumbersome in order to house components capable of withstanding high currents. Most ESP measuring devices (motor controllers) are designed to operate from 0 to 5 amps. To reduce or scale-down the actual current in the switchboard to an acceptable level, current transformers (CTs) are used. 7.2.2.1 CT Ratio's The CTs should be sized such that under normal operating conditions, secondary control amp levels are between 2.5 and 3.5 amps. This is done to obtain the best motor controller performance and to have the pen track along the center of the recording ammeter chart. To determine the correct CT primary, use the following formula: CT Size = Expected Amps thru Switchboard X 1.6 Example: 39 amp 990 required surface voltage of motor - MDFH Size 3, 1,500 volt switchboard. CT Size = 39 X 1.6 = 62 Choose a CT with a ratio as close to 62:5 as possible. (In this case a 75:5 Ratio) (39/75) 5 = 2.6 Amps The following list contains the combinations which can be used to select proper secondary control amp levels: Primary Current Current Transformer Turns of Wire Through Switchboard Ratio Through Window 120-210 amps 300:5 1 60-105 amps 150:5 2 40- 70 amps 100:5 3 30- 52 amps 75:5 4 As you will note, there is a gap in the primary current ranges between the 300:5 and the 150:5 ratios. For this reason, REDA also utilizes the 200:5 and 150:5 combination current transformers. The 150/200:5 combination current transformer is of the doughnut type. Its construction is such that it can be used as either ratio by changing hookups. Figure 7A is a sketch of the type presently used.

I am not sure I understood your question. But here is the answer:

It is correct. The relay setting 0.5 x In is equivalent to 150 A setting in primary circuit.

Depending on the IDMT characteristic setting and time multiplier setting, the relay will trip according to the curves on page 20-24 of the relay manual (http://library.abb.com/global/scot/scot229.nsf/veritydisplay/e443faf99f1d91f9c12572a0004710e4/$File/FM_SPAJ140C_750629_ENdad.pdf)

With the IDMT characteristic setting = 'Normal Inverse-time characteristic' and time multiplier (k) setting = 1, if 300 A current (twice the setting) flows in primary, the relay will trip at 10 seconds (see Fig 7 of page 22 of the manual).

- MS

The SPAJ 140 C relay has got setting for 1 amp secondary as well as 5 Amps secondary.

This can be choosen based on the CT provided in the Power circuit.

Therfore In can be 5 or 1 depending on selection.

Setting for definite time current can be 0.5 In to 5 In.

In your case In =5

Therefore secondary currents range will be 0.5x=2.5 amps to 5X5=25 amps

Primary current range will be 2.5 x300/5=150 Amps to 25 X300/5=1500 Amps.

Since setting is 0.5, primary current would be 150 Amps.

Hope this is clear to you