2.1 The fundamental functions
The LIM function is to calculate the max. value of the total hazard
current that would flow through a solid connection between the
isolated current carrying conductor associated with the higher
impedance and ground. The total hazard current is displayed
on a 7-segment LED display and an analog bargraph with 16
LEDs. The level will increase as additional loads are connected
to the system or when a ground fault is slowly developing or has
occured.
The bargraph has two scales, one for 2mA and one for 5 mA alarm
setting. The two yellow LEDs on the left near the bargraph
indicate, which alarm setting is selected and which scale is valid.
There is a visual and audible alarm when the total hazard current
exceeds the setting of either 2 or 5mA. The visual alarm remains
during duration of the fault, the buzzer can be muted at any time.
When muted, the yellow LED inside the mute button comes on to
indicate a muted condition.
Activating the test button starts the following procedures:
- Audible alarm check
- Illumination of the analog LED bargraph
- Illumination of the 7-segment LED displays of the total hazard
current and the optional transformer load
- Internal hardware check and self calibration by using internal
faults (the numeric Display of the optional transformer load
indicates CH or CL depend on 120 or 240V).
If these tests are successful, the LIM goes in the operating
condition, otherwise the LIM displays an errorcode. After the fault
of the error has abolished it works again in the operating condition,
when the internal tests are finished.
The LIM also performs an internal hardware check and a
self-calibration after 3 hour and then every 12 hours. If this checks
aren´t successful the LIM displayes an error-code too.
The LIM has provisions for connecting one or two remote
indicators with or without meter or digital display. Relay output
contacts are also available which can be wired into a circuit to
trigger an external alarm.
2. General Information
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