Safety Circuits

The User Control Console includes three safety circuit components.

  • GFCI (Ground Fault Circuit Interrupter)

  • LIM (Line Insulation Monitor)

  • ROV Power Safety Interlock

GFCI (Ground Fault Circuit Interrupter)

The GFCI protects the operator from shock from the AC circuit of the power source.

The GFCI is inline with the power cord. When initially connected to a power source, it is in the Off state. You must press the Reset Button to enable it. When enabled, the green LED will be illuminated.

When using a power source that includes a GFCI, the VideoRay supplied GFCI is not needed and can be removed from the power cord.

LIM (Line Insulation Monitor)

The LIM protects the operator and persons in the water nearby from shock from the DC circuit of the tether. While the GFCI switches are part of the GFCI component and must be turned on to operate the User Control Console, the LIM is automatically enabled when the system is turned on. The LIM operates on a principle similar to the GFCI and monitors the quality of the insulation of the conductors. If the resistance between the conductors drops below the safe threshold, the LIM will trip.

The MSS LIM is two stage. When the LIM detects the resistance between the ROV power conductors falls below 900 kOhms, the yellow LIM Alarm A1 LED will turn on, but the power circuit will remain on. When the LIM detects the resistance falls below 200 kOhms, the yellow LIM Alarm A2 LED will turn on and the ROV power circuit will be disabled. The LIM can be reset by pressing and holding the R button. The yellow LIM Alarm light should turn off. To test the LIM, press and hold the T button. If the LIM continues to trip, the system should be inspected for a fault before being used.

The LIM has additional features that are described in more detail in the LIM Module Manual.

ROV Power Safety Interlock

The ROV Power Safety Interlock prevents the ROV power from being engaged unless an ROV is plugged into the tether. This feature protects users from accidentally contacting the ROV power circuit of an open tether connector.

See the User Control Console Switches and Connections section for more information about these components and their locations, and see the Pre-Dive Preparations section of the Quick Start Instructions for information about testing these components.


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MSS Defender Operator's Manual, Version: 1.00.00
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