Factors influencing human errors during work permit issuance by the electric power transmission network operators

Abstract

Prediction, identification, and control of errors effect on human performance and improve human actions. Human reliability has an important role in increasing the reliability of electricity production, transmission, and distribution networks and its direct/indirect damages. Right implementation of an effective work permit issuance system can meet safety of employees working in the control centre and other facilities and also can increase reliability of being used facilities. In the present research, effective factors for human errors in the process of work permit issuance by operators of control rooms working in the electricity transmission stations were studied. Substation operators’ tasks, as the main human errors sources in the process of work permit issuance, were analyzed using hierarchical task analysis (HTA). Errors related to tasks were then predicted using systematic human error reduction and prediction (SHERPA) technique. The process of work permit issuance, as one of the main operators’ tasks in which errors can be traced, was selected to analyze the impacts of some variables such as age, work experience, education level, hours of training, and number of maneuvers (number of permits issued by each operator). In the end, relationship between above variables and recorded errors was determined through Spearman’s correlation coefficient. The results reveal that the action error and the error of maneuvering task have the most frequency respectively among the 107 predicted errors in six main tasks and 61 subtasks. The results also indicate a significant correlation (confidence level=95%) between the number of errors in the work permit issuance process and the Number of maneuvers (number of issued permits) (correlation coefficient=0.31 & P=0), Training period (correlation coefficient=0.195 & P=0.014), the work experience (correlation coefficient=0.191 & P=0.016) and the age (correlation coefficient=0.164 & p=0.014). There is also no significant correlation between the education level and the number of operator’s errors in the work permit issuance process (correlation coefficient=-0.064 & P=0.413). A reduction in human errors can be expected through the application of the identified factors effecting on operators’ errors in power production and distribution networks. Keywords: Operator, Work permit, Human error, HTA, SHERPA