1. ## Fanuc 5M motors

I need to know:
V, I nom, I stall

I purchased CNC mill with fanuc 5M controller (out of order and no manuals).
There are following motors:
X,Y - Fanuc DC Servo Motor Type 5N-2500M (year 1979)
Z - Fanuc DC Servo Motor Fanuc Gettys Type10-2000M (year 1979, 8 brushes)
no other information available :-(

Oscar

2. p.s. Transformer is 3 phases and output label say 90V an each phase.
May be some can measure at least voltage, amperage then I will determine myself.

3. Fanuc DC Motor 0
Type: 0-2500M 2500 pulse encoder
Permanent Magnet DC Servo Motor
Output Power: 0.4 KW (0.5 HP)
Rated Torque: 28 Kg-Cm
Max. Torque: 240 Kg-Cm
Max. Speed: 2000 Rpm
Rotor Inertia: 0.029 Kg-Cm-S 3
Back EMF Constant: 25 V/K RPM
Torque Constant: 2.44 Kg-Cm/Amp
Mechanical Time Constant: 25 mSec
Thermal Time Constant: 50 Min
Weight: 12 Kg

Fanuc DC Motor 5
Type: 0-2500M 2500 pulse encoder
Permanent Magnet DC Servo Motor
Output Power: 0.8 KW (1 HP)
Rated Torque: 55 Kg-Cm
Max. Torque: 480 Kg-Cm
Max. Speed: 2000 Rpm
Rotor Inertia: 0.05 Kg-Cm-S 3
Back EMF Constant: 50 V/K RPM
Torque Constant: 4.87 Kg-Cm/Amp
Mechanical Time Constant: 15 mSec
Thermal Time Constant: 55 Min
This is some notes I made when I was looking for similar information and found them in various sources:
equations are:
1. V=Ia R + Ke omega (Ia=armature current, R=armature resistence,
Ke=electr. constant, omega=speed)
2. Tg=Kt Ia (Tg=costant, Kt=torque constant)
3. Tg=J d(omega)/dt (J=inertia, d(omega)/dt=accel.)
The DC motor transfer function is:
Gm(s)=(1/Ke)/(1+s(Rj/KtKe)), which can be written Gm(s)=(1/Ke)/(1+sTm)
where Tm=mechanical time constant.
To measure the parameters you are asking for, I suggests the following:
A. Measure with an ohm-meter the armature resistance, then apply voltage to the motor without load and measure the current and speed. From equation 1. you can easily derive Ke.
B. Apply nominal current to the motor (with the shaft locked) by means
of a variable voltage source. Measure the torque on the shaft. From this you can derive the torque constant Kt=Torque/Amp.
C. You will find that Kt is approx. equal to Ke
D. For the inertia you can obtain it by calculation from the size and
material of the rotor.

Note1: inductance can be ignored- the electrical time constant is
very short compared to the mech time constant so that it can usually be
ignored.
You can measure the mech time constant by running the motor up to
speed at no load, disconnecting the supply and letting it coast down- plot speed vs time and fit to exponential N=No(e^-t/Tm) time to drop to 36.8% of original speed is the time constant.

Note2: If it is a permanent magnet motor, you can determine the internal emf by spinning it at rated speed and measuring the open circuit voltage. The voltage at any other speed will be directly proportional to speed. To measure the winding resistance, lock the rotor so it doesn't turn and measure the current with a small voltage applied (so as not to exceed rated current) Don't bother using a multimeter's ohm range- not worth the effort.
For inductance, you should use a scope- apply a voltage, rotor locked and look at the current trace vs time.
This will be of the form i=K[1-e^Rt/L] where i is the current at time t.
In most cases the inductance can be ignored as its effects are generally swamped by the mechanical inertia in transient cases and is of little importance for steady state.

Al.

4. Thank you Al!

I know this information from previous posts.
Not exactly what I need....

• Originally Posted by oskars

V, I nom, I stall
You wanted these, They should all be there in what I posted, or at least the way to obtain them easily.
I forgot to mention, for the sake of calculation these motors are rated at about 1200rpm, 1500 tops so for e.g. on the 5, it would be BEMF 50v/krpm = 150vdc.
Al.

• Al,
You are right!
Thank you!!!
I will try to do calculation.
Oscar

• found on ebay, very similar to my motor:
Fanuc 5M A06B-0642-B005 (0) DC Servo Motor, No M-183400, Date 81.12

TORQUE CONT. AT STALL 5.9 Nm
AMP CONT. AT STALL 9A
VOLT 151V
RPM 2000rpm
TACHO VOLT 6V/Krpm
AMB TEMP 40C