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Function
A
sensor picks up the sum current of L1, L2 and L3 and is mounted on all
three cores of the cable. Normally, the sum current of the phases L1,
L2, L3 is approximately 0 A. If there is an earth fault in one of the
core, the sum current will increase due to this asymmetric situation.
This increased current will be detected and transmitted to the reading
instrument for evaluation.
The earth fault will be indicated if the fault current has reached the
preadjusted operating point.
Current peaks, caused by switching on big engines, transformers etc.
can reach the operating point and lead to a wrong evaluation. In order
to avoid this, the incoming impulse must be filtered. That means that
the earth fault will only be indicated, if the impulse is longer than
the preadjusted minimum impulse duration. This duration can be adjusted
in the range of 40 to 300 ms. The earth fault is indicated by all
indicators between the net-input and the location of the fault.
Therefore, the fault is between the last indicating instrument and the
next instrument in stand-by mode. |
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Assembling
(refer
to assembling instruction)
It is very easy to install the EASI indicator. For assembling the
sensor, a steel tape has to be disconnected from one side of the housing and has to be wrapped around the three-core-cable
(or
around three single-core-cables). Now the housing of the sensor and the steel tape have to be connected
again.
To ensure a clear indication, the cable screen must be led back within the steel tape of the sensor
(neutralization of the screen current).
The reading instrument of type EASI-ER must be slided into a
panel-cutout
(91.5+0.8 x 44.5+0.6 mm DIN43700).
This panel-mounted instrument can be opened by removing the front
cover; in this way the switches for selecting the adjustment values are accessable.
The EASI-R reading instrument (surface-mounted) has to be installed on
the wall with two screws according to the assembling instruction. After
removing the cap of the housing, the requested adjustment value can be
chosen. The possible values are presented on on the inner side of the
cap.
Adjustable are:
a) max. 6 trip currents
b) 4 times for minimum impulse duration
c) 4 reset times
The sensor and the blinking lamp have to be connected according to the
wiring diagram shown on
the housing of EASI.
When the assembly is completed, a functinal test should be carried out
(via test button).
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Technical
Data
reading
instrument |
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| dimensions of the
housing: |
EASI-R
(surface-mounted) 105 x 76 x 43 mm
EASI-ER (panel-mounted) 96 x 48 x 63 mm
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| adjustable operating
current: |
max.
6 values in the range of 10 - 300 A +/- 10% |
| minimum impulse
duration: |
40
ms to 300 ms |
| temperature range: |
-20
Celsius.... 70 Celsius |
| power
supply: |
lithium
battery 3.6 V |
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| relay contact (one changer): |
max. 250 V AC / 125 V DC |
| switching current: |
max. 1 A |
| breaking capacity: |
max. 50 ..150 W (depends on
operating voltage) 250 VAC |
sensor:
dimension of the housing: |
(W*H*D)
39*39*26mm, standard cable length 3 m
with infinitely variable fixing tape.
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