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FEM Duty Information

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
    1. Load Q = 3000 kg
    2. Hoisting speed v = 8m/min (2 ropes)
    3. Average hoisting height H = 3m
    4. Number of work cycles N = 16/h
    5. Daily working time T = 8 h
    6. 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