Over -Temperature; Earth Fault - ABB DCS 500B Description

Functional Software description
Over -
temperature

Earth Fault

66
When the level is adjusted, the signal I TRIP A is updated auto-
matically.
Note. With converter type C4 the nominal values must be given to
the program with parameters 517...521.
When the overcurrent limit is exceeded, an OVERCURRENT-fault
will appear (fault code 2).
The maximum temperature of the bridge can be read out from signal
MAX BR TEMP (10512), scale: 1 = 1°C. If this limit is exceeded, a
CONVERTER OVERTEMP-fault will occur. The alarm limit is 10°C
below the tripping limit. Actual bridge temperature is given by signal
BRIDGE TEMP (10507), (scale 1 = 1°C).
With converter type C4 the maximum temperature of the bridge
must be given to the program with parameter 519.
Earth fault indication is based on a sum current transformer in the
supply. The sum of three phase currents is zero, if there is no earth
current.
SUPPLY
EARTH.CUR SEL
A
EARTH.FLT LEV
EARTH.FLT DLY
M
Figure 46 Principle of earth fault current measurement
Earth fault protection is activated by parameter
EARTH.CUR SEL (514).
0 = not used
1 = activated
Earth fault current tripping level is defined by parameter
EARTH.FLT LEV (515).
(scaling in amps)
The time after which fault is activated is defined by parameter
EARTH.FLT DLY (516).
(scaling 0.001s)
COMP
D
t
I1 > I2
Delay
DCS 500 Software Description
0
Earth
fault