Page 556 - Mechanical Engineers' Handbook (Volume 2)

3 Direct-Current Servomotors 547

Table 2 dc Servomotor Classification
Typical Steady-State
Motor Type Configuration Characteristics Salient Features
Permanent magnet No power required for field
generation
Runs Cooler
Torque-speed characteristics
is linear
Compactness

Straight series Large starting torque

Split series Allows quick reversing

Shunt Low starting torque
Finite speed at zero torque

Compound High starting torque
Complex circuitry required
for reversing

Table 3 Upper Limits of dc Servomotor Performance
Maximum Maximum Torque/Inertia Maximum
Power Speed Ratio Bandwidth
2
Motor Type (hp) (rmp) (rad/s ) (rad/s)
Moving coil 0.5–1 4500–5500 200–250 1500
Printed circuit 7 3000–4000 130–220 1000
Permanent magnet 10–15 850–3000 15–30 100

Source: From Ref. 4.