DataNotes on useThis worksheet can be used to study coordination
between a fuse, a feeder relay (A) and an upstream relay (B) with a
motor starting load fed by a feeder. CT primary currents to be
filled in B15 and D15 for the relays and fuse rating in C15A
typical motor load with staring current of 600 amps and starting
time of 6 sec. Is shown in column JCells M15, N15 and O15 contain
the characteristic equation of Standard Inverse (SI), Very Inverse
(VI and Extremely inverse (EI) relays. Do not worry about the
current values being displayed in the cells.Copy and paste the
contents to H15 and I15 (depending on the desired type of relay as
noted in C16 and D16).Use autofill to calculate other rows. Delete
contents which are not positive (Negative values, 0 and Div/0!)Turn
over to the worksheet CURVE which will display the information
graphicallyCoordination changes can be effected using PSM (Plug
setting multiplier) and TMS (Time multiplier setting) as required
(or even the CT primary value)Typical fuse equations are indicated
in M18:P19. Copy and paste the cell content for the selected
fuse.Do not fill cells below 200% of fuse ratingTo simulate the
addition of a definite time high-set element, replace cell contents
with the set delay.In such cases, it is better to introduce another
row so that both IDMT and DMT values at the set point can be
represented.Operating time (seconds)CircuitFuseRelay ARelay
BCurrent in AmpsFuseRelay ARelay BMotor StartSIVIEIPrimary
Amps1001008003007.330.000.000.00Relay
curve****SISI3106.876.12PSM****113206.455.95TMS****113306.065.79Fuse
100Fuse 150Fuse 200Fuse
2503405.715.655.7115.5727.8547.583505.395.523605.095.403804.575.174004.134.986.004503.264.586.005002.644.286.005502.184.046.006001.833.846.006001.833.840.016501.563.677001.353.537501.173.408001.033.308500.913.20115.399000.813.1259.369500.733.0440.6610000.662.9731.3020000.172.277.5730000.071.995.2340000.041.834.2850001.723.7560001.643.4070001.583.1680001.532.9790001.492.82100001.452.70200001.252.11300001.161.86400001.101.72500001.061.621000000.941.38
