Explain about PSM and TSM ?

Plug Setting Multiplier (P.S.M.): The ratio of fault current in relay coil to the pick-up current is called Plug Setting Multiplier (P.S.M.).

Mathematically it can be express as,

Plug Setting Multiplier (P.S.M.) = $\frac{Fault current in relay coil}{Pick-up current}$ = $\frac{Fault current in relay coil}{Rated secondary cuurrent of C.T.x\% Current setting}$

For example, suppose that a relay is connected to a 400/5 current transformer and set at 150%. With a primary fault current of 2400 A, the plug-setting multiplier can be calculated as under : 

Pick-up Current = Rated secondary current of C.T. $\times$ % Current setting = 5 $\times$ 1.5=7.5 A

Fault current in relay coil = $2400\times \frac{5}{400}= 30 A$

Plug Setting Multiplier (P.S.M.) = $\frac{30}{7.5}=4$

Time Setting Multiplier (T.S.M): A relay is generally provided with control to adjust the time of operation. This adjustment is known as time-setting multiplier. The time-setting dial is calibrated from 0 to 1 in 0.2 steps of 0.05 sec (see Figure - 01). These figures are multipliers to be used to convert the time derived from time/P.S.M. curve into the actual operating time. Thus if the time setting is 0.1 and the time obtained from the time/P.S.M. curve is 3 seconds, then actual relay operating time = 3 $\times$ 0.1 = 0.3 second.