can series fields be changed to shunt fields
can series fields be changed to shunt fields
(OP)
Hi guys, need help, I just obtained a 9.5 hp dc motor from a forklift. I want to run a sundstrand hydraulic transmission with a hydraulic pump piggybacking on the end of trans. When I took the cover off the motor I find two large bars marked A1and A2 which are the armature, also there are: 1 wire marked S1, 2 wires together marked S2, 3 wires together marked S3, 2 wires together marked S4, 2 wires together marked S5 and 2 wires together marked S6.
The S1,S2,S3 all have continuity between them but nothing to the A wires or S5 and S6, S5 and S6 have continuity between them only. Also the S wires are about #6 or #8 wires. The tag says it is a 4 speed motor (GE motor) I am thinking that the S Wires are series fields but the guage of the wire seems too light, the armature is rated at 290 amps, On connecting the motor up as a series with the A wire going to field wire S1 and then using the S3 wires to the battery the motor runs with a small current draw of only 15 amps, I am thinking that perhaps there is a way to hook this up as shunt wound, is it possible to run a series field as a shunt field? I would prefer a shunt wound so that my RPM would be steady. Can I play with the fields to get a higher rpm, any suggestions on how to test this motor would be appreciated.
Ellery Deuville
The S1,S2,S3 all have continuity between them but nothing to the A wires or S5 and S6, S5 and S6 have continuity between them only. Also the S wires are about #6 or #8 wires. The tag says it is a 4 speed motor (GE motor) I am thinking that the S Wires are series fields but the guage of the wire seems too light, the armature is rated at 290 amps, On connecting the motor up as a series with the A wire going to field wire S1 and then using the S3 wires to the battery the motor runs with a small current draw of only 15 amps, I am thinking that perhaps there is a way to hook this up as shunt wound, is it possible to run a series field as a shunt field? I would prefer a shunt wound so that my RPM would be steady. Can I play with the fields to get a higher rpm, any suggestions on how to test this motor would be appreciated.
Ellery Deuville





RE: can series fields be changed to shunt fields
Connected in shunt or parallel to the power line will result almost in a short circuit.
Then, I do not recommend series windings being connected in parallel to the line terminals due to the destructive heat generated by the quasi short circuit current (i^2*R).
RE: can series fields be changed to shunt fields
In short... a series field will have to stay a series field..but to play around with speed...you could vary the supply voltage...all trial and error though!!
hope this helps
JEFF
www.motors-direct.co.uk
RE: can series fields be changed to shunt fields
A shunt motor has slightly different operating characteristics than a series motor,since the shuntfield coils are made of finer wire,as to series motors were the series ciols are in series with the armature and pass the same current.so your answer is no.
RE: can series fields be changed to shunt fields
RE: can series fields be changed to shunt fields
Thanks again
Ellery
RE: can series fields be changed to shunt fields
More modern forklift trucks that use solid state controllers for the propulsion use shunt wound motors and even permanent magnet motors. This is because the solid state controller measures motor current and voltage and matches what the switching power converter does to match applied voltage so that the motor operates smoothly when at less than full speed. At less than full speed a shunt wound motor will have a countervoltage that is significantly less than the battery voltage.
The advantage of a shunt wound motor with a solid state controller is that you can get full torque from zero to 100% speed as opposed to torque dropping off as speed increased in the case of series wound motors. The more sophistocated controllers for modern railroad traction motors also have the ability to turn around the switching power converter so that the motor can pump energy into the line or a resistor, what is known as regenerative braking and dynamic braking respectively.
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As a bit of historical note, steam locomotives for hilly terrain could turn their pistons into air compressors to effect dynamic braking. This was done with 5 throttle valves arranged as:
1. Live steam to piston ( controlled power output )
2. Air into piston
3. Air out or piston ( controlled dynamic braking )
4. Dead steam to stack ( produced draft )
5. Live steam to stack ( produced draft at standstill )
Early electric locomotives also had air compression pistons hooked up to the wheels for dynamic braking because stainless steel a.k.a. nichrome resistance wire had not been invented yet. Switzerland also had some electric/steam hybrid locomotives that used heat stored in a boiler to operate steam pistons when operating on sidings that were not electrified.
RE: can series fields be changed to shunt fields