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Elektrotechnische Anlagen GmbH
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Troubleshooting and fault elimination
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The five LED's in the cover of the power feed/feedback unit display the operating condi-
tion. For easier visibility during service and first powering up similar LEDs are placed on
the control board.
Stop!
If the power feed/feedback unit trips during retardation, it must not be reset until the end of the
retardation and until the DC-bus voltage has fallen to normal values.
To avoid any kind of problems you can block the impulse-release of the inverter by connecting
the collective-error-relay-contact of the power-feed/feedback-unit with the corresponding con-
nection of the frequency inverter.
U
CE
-tripping:
The power feed/feedback unit trips by the U
CE
-protective-circuitry, if the specific maxi-
mum current of the device is exceeded. The principle of this protective-circuitry implies
that for a short time (less than one millisecond) the IGBT is stressed over its specification
for normal operation. For an single case this means no problem for the power
feed/feedback unit. However, if the over current cut off arises often or even periodically,
the high power semiconductors will age very rapidly and fail premature.
The cause of periodical U
CE
cut offs may be over load, under voltage in the network, a de-
fective or oscillating controller, an oscillating reference input or a wrong design of the
plant.
STOP