Plug setting multiplier (PSM): It is related to the current setting of the overcurrent relays. The plug setting multiplier is defined as the ratio of the ‘transformed fault current on the relay side’ to the ‘relay pickup current’.
Time setting multiplier (TSM): It is related to the operating time of the relay during faults. The angular distance through which the relay disc travels during faults before the trip contacts close is varied to get different times of operation of the relay. This is time setting. These times of motion of the disc are set in 10 steps starting with maximum time setting of 1 (when disc is set farthest) to minimum (when disc is nearest) of 0 (instantaneous). For example if the angular travel from trip contacts is set to maximum then TSM =1, then for a particular PSM if the operating time of relay is 1 second then for the same PSM if the TSM is set to 0.4 then the time of operation will be (1 second x TSM) = 1 x 0.4 = 0.4 seconds.
Thus TSM is used to define the steps for time setting of relay operation.