| Selection of Suitable FEM - Group | ||||
|---|---|---|---|---|
| Criteria for Hoist Type According to Working Conditions | ||||
| Load Spectrum | Average daily operating time | |||
| Light | t <= 2 | 2 < time <=4 | 4 < time <=8 | 8 < time <=16 |
| Medium | t <=1 | 1 < time <=2 | 2 < time <=4 | 4 < time <=8 |
| Heavy | t <=0.5 | 0.5 < time <=1 | 1 < time <=2 | 2 < time <=4 |
| Severe | t <=0.25 | 0.25 < time <=0.5 | 0.5 < time <=1 | 1 < time <=2 |
| Hoist Group | FEM1Bm | FEM1Am | FEM2m | FEM3m |
| Duty Factor | 25% ED | 30% ED | 40% ED | 50%ED |
| Starts | <= 150/hr | <= 180/hr | <= 240/hr | <= 300/hr |
Selection is based on:
- Load Spectrum
- Average operating time per day
- Daily working time
- Starting frequency
- The basis for calculations according to FEM standards is a 10 years lifetime for hoists
- The FEM group is determined by the daily operating time and the load spectrum
- The selection of the correct FEM group enables us to find the most suitable size of hoist for different applications
The FEM group also specifies the ED% and the starting frequency of motors
Selection of suitable FEM group
Instruction:
- Select the load spectrum type
- Follow the load spectrum to the right, across the table and compare your average operating time per day value (t) to the limits in the table.
- Stop where your calculated value (t) is between the limits.
- Move down that same column to get your hoist group, duty factor, and maximum starts per hour.
Example
- Information
- Load Q = 3000 kg
- Hoisting speed v = 8m/min (2 ropes)
- Average hoisting height H = 3m
- Number of work cycles N = 16/h
- Daily working time T = 8 h
- Load spectrum: Heavy
- Calculation
- Average operating time per day
- t = (4 x H x N x T/ V x 60) hours (h) = (4 x 3 x 16 x 8/ 8 x 60) = 3.2 h which is < 4 h
- Number of starts per hour when two extra start-ups are estimated for each normal start
- F = 4 x 16 x 3 = 192/h which is < 300
- Solution
- According to table, hoist group FEM 3m. Select a hoist with this rating