Does anybody know how to measure/work out strenght of electrolyte in Liquid Resistor starter

we currently use an AIOP System to control the start and run a 8000 hp motor driving a mega shredder shredding scrap


the motor runs with a 8 % fixed slip when its running

Electrolyte type and strength is dependant upon a number of factors including tank size/volume, start torque and start time, number of consecutive starts to hot, number of starts per hour, ambient temperature, whther the unit is fitted with a heat exchanger etc etc. The fact that this unit is operating in slip control mode also needs to be taken into consideration.

I therefore suggest you speak to AOIP or distributor. If you have the above information handy, it will make it easier for them to provide you with the guidance needed.

Regards,
GGOSS

Please also be aware there are procedure for the handling and disposal of electrolyte. Make sure you consult the vendor and any relevant authorities.

Regards,
GGOSS

thanks for info perhaps i did'nt explain problem well enough see below

The main reason for trying to get some sort of benchmark for the solution when the system was set up 25 kg of electrolyte salt was added as per nameplate we had touble with the solution overheating after many phone calls to manufacturer it was decided to add an extra 75 kg of electrolye salt
we have changed the electrodes recently (worn out after 4 years service) and refilled tank with water and 100 kg of salt since then we have had trouble with motor tripping out with overcurrent

any thoughts would be appreciated

That dosage sounds extremey high. Which EPM starter model do you have installed? Also, by motor runs at 8% slip, do you mean the starter is always in circuit with electrodes partly separated eg no rotor shorting contactor or are you achieving that via external fixed resistors? Also, is your starter fitted with a heat exchanger?

We do quite a bit of work here with metal recyclers and have starters installed on shredders to approx 5,000hp. The dosage used is different to that of a standard starting arrangement because the electrodes are always in circuit and the electrolyte is hot thereby giving a different characteristic. In these installations the electrodes are manually controlled eg the machine operator keeps a closeful watch on shredder loading and drives the electrodes in or out subject to conditions at the time. That process can be automated and whilst I do not fully understand they don't do that, it's keeping people in a job so who am I to argue that.

The starters I refer to are not AOIP EPM, use a different type of electrode configuration and movement strategy. The electrodes can be moved from the fully seperated to fully closed positions and vice versa in a very short period of time and are therefore well suited to shredder applications. Operators here drive them very hard, 4 years service life from electrodes from a starter used in this manner is unheard of!

Back to your over-current trip issue this could well be related to the electrolyte mix or just a shredder operation/loading issue. I'll run your issue past a couple of people I know here and if there's anything I can add I will come back to you.

Regards,
GGOSS