Description: Ratio of the power requirement of the pump reduced by the mechanical power losses  to the power requirement of the pump under certain working conditions.; Name: mech eff
Description: proportion of the pump power input, p, available after satisfying the mechanical power losses, pj,ab, at given operating conditions; Name: mechanical efficiency
Description: variable quantity, which is not influenced by the control but is introduced into the control system from outside with the aim of making the final controlled variable follow it in a given relationship; Name: command variable