CONFIGURATION 
Part. No. 2400M2501_6    Touchpoint Pro 
  94  Technical Handbook 
10.2.1  TWA Start of First Shift Time 
This setting is not used by the LTEL calculation and does not need to be changed.   
10.2.2  LTEL Algorithm 
The CCB will calculate the moving average of the LTEL for an 8-hour time interval. 
LTEL = (TEN_MIN_TWA1 + TEN_MIN_TWA2 + → + TEN_MIN_TWAN) / LTELN 
Where: 
  LTEL = Long Term Exposure Limit TWA 
  TEN_MIN_TWA1 = 1st Ten-Minute TWA 
  TEN_MIN_TWA2 = 2nd Ten-Minute TWA 
  TEN_MIN_TWAN = Nth Ten-Minute TWA 
  LTELN = Number of Ten-Minute TWA Samples received in 8 hours 
 
CCB will use the Ten-Minute TWA for LTEL moving average calculations: 
TEN_MIN_TWA = (HM_TWA1+ HM_TWA2 → + HM_TWAN) / TEN_MINN 
Where: 
  TEN_MIN _TWA = Ten-Minute TWA 
  HM_TWA1 = 1st Half-Minute TWA 
  HM_TWA2 = 2nd Half-Minute TWA 
  HM_TWAN = Nth Half-Minute TWA 
 
The CCB will add the ‘Half-Minute TWA’ samples received in 10 minutes and then divide it by the TEN_MINN to calculate 
the ‘Ten-Minute TWA’. 
Every half minute the CCB updates LTEL TWA by discarding HM_TWA1 and adding the latest HM_TWAN. 
Every 10 minutes the CCB recalculates the LTEL TEN_MIN_TWA and divides it by ‘TEN_MINN’ to give a new reading.