I like to know if there is any way to diy a load bank , for example , simulating a motor load ...

 

Yes (my answer is just as specific as your question)
Need much more information (i.e. electrical specs required)

Have you even tried to google "DIY Load bank"

 

A bunch of high power resistors?

You need to specify what the load is you expect and what power dissipation you need to handle.

You could also consider an electronic load - which uses semiconductors such as transistors and MOSFETs - to simulate a constant current, constant power or constant resistance load. However, it will almost certainly cost more.

 

What voltage and current or VA rating is the motor?

 

I built a 3000W load bank for UPS systems, using ceramic lamp bases and standard 200W incandescents.

It is split into two seperate 1500W sides, and smaller units can be tested by unscrewing some of the bulbs, or using smaller wattage ones.

Motors have inductance and capacitance that makes their response as a load different than a non inductive(resistance only) load. You pretty much need a motor to 'simulate' a motor, for anything other than plain max load testing.

 

Sorry for lack of information given. My dc motor is a 6V with a stall current of 1.8A, Power rated is roughly at 2Watt.

 

Quick and dirty power resistor.

Use the element from a cheap toaster, or from your sisters hair dryer. Use alligator clips and connect at the ends, then move towards the other end till you achieve the power level you need.

At 6 or 12 volts the heating elements from 110V equipment works just fine as a high wattage resistor. You want to use enough length between alligator clips so the wire doesn't radiate and glow red. That is the current limit.

 

Get a single 3.3 Ohm 20W power resistor, or three 10 Ohm 7W or higher power resistors and wire them in parallel.

 

Is it simple to build a load bank that has variable value of current for different value of resistance ? I found a circuit that could have different value of current but somehow i could not simulate it properly (what i mean is that turning the potentiometer does not give any changes to the output value at the voltmeter) . The potentiometer supposed to be able to vary the current but it doesn't seem to work in simulation. I found the circuit from the link below

http://electronicdesign.com/article/power/self-powered-dummy-load-checks-out-multiple-output.aspx

 

Remember that a simple resistor won't simulate the reactive part of the motor's behavior, should that be important to you -- nor the startup characteristics (which, in turn, depend on the motor's mechanical load). The startup characteristics could be emulated with an active device like a MOSFET, but I'll have to defer to the EEs to see if they have some way to simulate the inductive part of the impedance. Should either of those things be necessary to you, you're going to need some help from an experienced EE.

 

Electronic Loads