Siemens TIASTAR Instruction Manual - Page 40
Browse online or download pdf Instruction Manual for Industrial Equipment Siemens TIASTAR. Siemens TIASTAR 44 pages. Motor control center
Print Page
Hazardous voltage.
Will cause death or serious per-
sonal injury.
Disconnect power before working
on this equipment.
Problem
Blowing of motor power fuses.
Blowing of primary control
transformer fuses.
Blowing of secondary control
40
Probable Causes
Short circuit on the load side of the
motor fuses.
Jogging or too frequent starting.
Fuses internally damaged because of
improper handling.
Shorted primary wiring in control
transformer.
Fuse may be "open" due to rough
handling before installing.
Secondary fuses not properly coordinated.
Abnormal current or short circuit in
Corrective Action
Use megger and other test instruments to
locate fault and correct.
On frequent starting, fuses accumulate abnormal
heat and cool more slowly than do overload
relays. Since fuses more closely follow cooling
and heating of motor windings, successive
starting operations must be limited to the safe
capacity of the motor to prevent fuse blowing
from this cause. Check size rating on fuse
against motor full load currents and service factor.
Motor power fuses may be damaged, dropped,
or roughly handled. Replace with fuse of same
type, rating, and voltage.
Replace or repair transformer.
Replace with fuse of same type, rating, and voltage.
Melting characteristics of secondary fuse should
not intersect melting characteristic of primary
fuse. Rating of standard NEC fuse should not
exceed twice the secondary current rating.
Check for shorted magnet coils, shorted rectifiers,
if supplied, grounds, loose or bent connections,
mechanical binding in relay and contractor
mechanisms, excessive operations, and incorrect
secondary terminal connections.
Siemens Energy & Automation, Inc.