Electrical Troubleshooting

First, identify what type of electric motor (induction, universal, stepping, etc.) you are using. This will identify which electrical parameter should effect the rotational speed.

Second, identify if any intended or accidental mechanical governor mechanism is regulating the speed. (Is something stuck?)

Third, identify if the scr driver for this motor is actually modulating the needed parameter.

Correct the problem accordingly.

Thanks. Mud pump motor is DC motor, speed control is done through motor armature voltage control from 0 to 750 volt DC. The voltage variations is done through Dc module. The dc voltage is generated from ac voltage by the help of controlled scr operation through ac module. Further there is no obstacle to prevent speed increase.

The driller in the Derrick floor uses hand throttle to to vary the speed. I just want to know how to find out the root cause where is the problem for non increasing the speed

measure the voltage at the motor! if you have voltage but no pumping you have hydraulic issues

Like other guys advice, measure output of the dc module if it is responsive to the variation of speed you want to have correspondingly. It could be the problem here. Knowing the results you should replace your dc module if voltage does not vary at all.

OK. You started down the path I described. It appears that my description of the initial steps were insufficient information for you to complete the rest of the steps. Exciting the armature field alone with a DC current will not cause motor rotation at all to happen. What creates the stator magnetic field? This will determine what kind of motor you have. This will then determine if the frequency of a field or the current of a field will modulate the motor speed.

There. All the information needed to fix it was to hand in the first place. If a competent Maintenance Technician is not on-board locally, then hire someone.

maybe its plugged with mud

Pelase first check the voltage and current of both the armature and field. Those can usually be read from the drive display but it's also a good idea to measure them using a DC (or TRMS AC which measures down to DC) clamp amperemeter (regular clamp meters only measure AC).

Also check the rating plate of the motor.

Dear Mr.dks,

You have not indicated the Type of Motor. If it is DC MOTOR, there again whether the field is in series or shunt, the problem is with main armature, or field winding.

If it is VFD there some thing related to TORQUE issue.

If it is AC conventional motor, the capacity of the motor is insufficient.

Pl. check and inform to this Forum.

DHAYANANDHAN.S

First I would check the driller control. Most pots are mechanical and can wear out. Simple check of the input voltage change as the driller adjust the pot.

For testing purposes, if safety requirements are met, it should be possible to control the DC drive using the local control panel (usually provided and mounted on the drive or sometimes on the door).

But you require the drive documentation and some basic knowldedge about DC drives. Unless it's a really old or basic DC drive or if the OEM has locked the panel or if the drive control panel hasn't been supplied. It will also allow you to check motor currents and voltages as well analog I/O values and digital I/O statuses.

Be aware that running motors using the drive control panel must be done very carefully as some safety systems may be bypassed (depends on the control design). For many non-servo applications, which by definition are not extremely dynamic by definition, it's possible to run carefully manually for testing purposes (if required set up temporarily an additional Emergency Stop pushbutton box). In case of running the DC drive in a regenerative quadrant avoid switching off the grid power unless absolutely required as it can blow fuses or even damage hardware.

Which DC drive model do you use?

hello Drilldog brother, Due to various operation problem I could not reply in time. with regards to problem, expert came checked , found problem lies in the DC module, replaced the module and tested OK- all this was done in a hurry, so I did not get the clue. Anyway problem resolved. Thanks for your very good reply anyway.

But I need your help further. The various step you had given, kindly expand a little bit. For example you said "Check the "Speed control" circuit at the SCR control" -- how to do this , please tell me the steps if it is OK with you

regards

HELLO SIR, THIS IS A BELATED RESPONSE FROM MY SIDE. I REGRET FOR THAT. YOU HAVE GIVEN A GREAT EXPLANATION TO SOLUTION OF MU PROBLEM. BUT BEING NEW IN THIS FIELD I AM UNABLE TO DO THE FOLLOWINGS :-

(1) How to Check the "Speed control" circuit at the SCR control. hat should be its input and output.

(2) also tell me how to Check at the Drillers control and what is the input and output of the driller's control panel

regards

dks

I have no practical experience with high pressure mud pumps. I have only theoretical suppositions.

I think it is a series dc motor. In my opinion, two problems could be: control problem [overspeed control limited] or short-circuit in excitation pole coil. For general information see:

http://www.iaeng.org/publication/IMECS2012/IMECS2012_pp1052-1054.pdf