--- title: "Individual, group and multi-motor drives" subject: "Utilization of Electrical Energy" chapter: 2 key: "semester_7/utilization_of_electrical_energy:individual-group-multimotor-drive" source: https://www.bctengineer.com/q/semester_7/utilization_of_electrical_energy/individual-group-multimotor-drive site: BCT Engineering --- # Individual, group and multi-motor drives Utilization of Electrical Energy · Chapter 2: Electric Drive System - Asked in: 2070 Chaitra - Video: [Classification of electric drives/Group drive/Individual drive/Multi-motor drive](https://www.youtube.com/watch?v=Sp6_SbnXuFA) — Read Electric Vehicle - Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14 - Page: https://www.bctengineer.com/q/semester_7/utilization_of_electrical_energy/individual-group-multimotor-drive - Whole chapter: https://www.bctengineer.com/md/semester_7/utilization_of_electrical_energy/chapter-2 ## Question Compare individual group and multi-motor drive system. ## Short answer Group drive: one motor runs multiple machines via line shaft; low cost, low efficiency, no individual control. Individual drive: each machine has its own motor; high efficiency, flexibility, fault isolation. Multi-motor drive: multiple motors on one machine, each for a mechanism; best control and automation, higher cost; used in cranes, rolling mills. ## Answer Electric drives are classified by how motors are arranged with respect to machines. - **Group drive**: one motor drives several machines through a line shaft, belts and pulleys. - **Individual drive**: each machine has its own motor (one motor may drive all mechanisms of that machine through gears). - **Multi-motor drive**: one machine has several motors, each driving a separate mechanism (e.g. an overhead crane with hoist, trolley and bridge-travel motors). ```text Group Individual Multi-motor M=shaft= M1-[m/c1] +--- machine ---+ | | | M2-[m/c2] | M1 M2 M3 | m1 m2 m3 M3-[m/c3] | hoist trolley | | travel | +---------------+ ``` | Point | Group | Individual | Multi-motor | |---|---|---|---| | Motors per machine | Fraction of one | One | Several | | Initial cost | Lowest | Medium | Highest | | Efficiency | Low (transmission losses, underloaded motor) | High | Highest | | Speed control | Not individually | Per machine | Per mechanism | | Reliability | Motor fault stops all | Fault stops one machine | Fault stops one mechanism | | Layout flexibility | Poor (line shaft) | Good | Very good | | Safety, cleanliness | Belts unsafe, noisy | Good | Good | | Control complexity | Simple | Simple | Complex (coordination) | | Automation | Difficult | Possible | Best suited | | Applications | Old workshops, small flour mills | Lathes, drilling machines, pumps | Cranes, rolling mills, paper and textile machines, machine tools | **Group drive** is cheap but wasteful and inflexible. **Individual drive** is the normal choice in modern industry. **Multi-motor drive** gives the best performance and automatic control for complex machines, at higher cost. ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. What is a multi-motor drive? A. One motor for many machines B. One machine with several motors, each driving a separate mechanism C. One motor per machine D. Motors in series Answer: B. E.g. an overhead crane with hoist, trolley and travel motors. (Key point: Multi-motor definition) 2. Which has the highest initial cost? A. Group B. Individual C. Multi-motor D. All equal Answer: C. Multi-motor needs many motors and complex control. (Key point: Cost) 3. Fault in one motor in a multi-motor drive stops: A. Entire factory B. Only one mechanism C. All mechanisms D. Nothing Answer: B. Each motor serves one mechanism. (Key point: Reliability) 4. Which suits a multi-motor drive? A. Small flour mill with line shaft B. Lathe C. Overhead crane or rolling mill D. Single pump Answer: C. Cranes, rolling mills and paper machines use multiple motors. (Key point: Applications) ## Related in Utilization of Electrical Energy - [Group vs individual drive; constant torque vs power](https://www.bctengineer.com/question.md?key=semester_7%2Futilization_of_electrical_energy%3Agroup-individual-constant-torque-power-drive) — Utilization of Electrical Energy, chapter 2 - [Group drive vs individual drive](https://www.bctengineer.com/question.md?key=semester_7%2Futilization_of_electrical_energy%3Agroup-vs-individual-drive) — Utilization of Electrical Energy, chapter 2 - [Closed-loop control of multi-motor drive](https://www.bctengineer.com/question.md?key=semester_7%2Futilization_of_electrical_energy%3Aclosed-loop-multi-motor-drive) — Utilization of Electrical Energy, chapter 2, asked 2× - [Group drive vs multimotor drive](https://www.bctengineer.com/question.md?key=semester_7%2Futilization_of_electrical_energy%3Agroup-vs-multimotor-drive) — Utilization of Electrical Energy, chapter 2 - [Types of electric drives with merits and demerits](https://www.bctengineer.com/question.md?key=semester_7%2Futilization_of_electrical_energy%3Aelectric-drive-types-merits) — Utilization of Electrical Energy, chapter 2 ## Related in other subjects - [Electric vs mechanical drive, individual vs group](https://www.bctengineer.com/question.md?key=semester_6%2Findustrial_power_distribution_and_illumination%3Aelectric-vs-mechanical-drive) — Industrial Power Distribution and Illumination, chapter 5 - [Number of V-belts for a motor drive](https://www.bctengineer.com/question.md?key=semester_6%2Fmachine_design_i%3Av-belt-number-of-belts) — Machine Design I, chapter 8 - [Electric drive and motor selection factors](https://www.bctengineer.com/question.md?key=semester_6%2Findustrial_power_distribution_and_illumination%3Aelectric-drive-motor-selection) — Industrial Power Distribution and Illumination, chapter 5 - [Series motor voltage to drive fan at 300 rpm](https://www.bctengineer.com/question.md?key=semester_4%2Felectrical_machines_i%3Aseries-motor-fan-400v-300rpm) — Electrical Machines I, chapter 4