Electric Motors and Diesel Engines

I think you need to think of the infrastructure that will be required for each type of drive & the purpose that each drive is expected to fulfill.

Diesel engines would generally be used in isolated areas when electrical infrastructure does not exist or will be difficult or costly to implement. Diesel engines also used for emergency [eg firepumps] applications when elctrical supply maybe interrupted.

Electrical motors generally cheaper and more reliable than diesel engines. In addition, for instantaneous starting, electrical motors may have the edge on diesel engines.

For classified [hazardous] areas, electrical motors maybe the easier & cheaper option.

What is the driven equipment and service?

thank's Hammer for answering me, the driven objects are pumps

and i wanna know will the hydrolic test readings be more acurrate in the case of motor than the diesel

Eh?

Hydraulic test measurements will normally be carried out with the pump not running, so as to confirm the ability of the wetted part of the equipment to sustain a given test pressure.

Dynamic test measurements will be carried out with the pump running so as to confirm, or even plot in the first case, the pump erformance curve.

Neither test is in any way related to the type of motive power used to turn the pump.