User manual GII Anti-Collision System
GIIMAN_US_CA_000_2021-06-15.docx © Gigasense AB Page 4 / 42
GENERAL – INTENDED USE
GIGASENSE II is an Anti-Collision System designed for Overhead Travelling (EOT) cranes or
other machinery running on a common set of rails.
In the most common case, where two EOT-cranes on the same track both need to be
protected from collision, two units are needed. When the crane should be protected from
running into a wall or track end, one complete unit (antenna and relay box) in combination
with one unit consisting of only the antenna and power supply (no relay box is needed) is
required.
The antenna is mounted with the center axis in the direction of movement, always pointing
towards the opposite antenna. The relay box is mounted apart from the antenna, normally
nearby the crane control functions.
Each unit works according to the SFCW (Stepped Frequency Continuous Wave) radar
principle, sensing the relative speed and distance to the reflecting transponder in the
opposite antenna. By using a modulated “fingerprint” reflection in the opposite antenna, the
system is not disturbed by undesired echoes from surfaces on the crane and other metal
parts.
The antenna is powered by the relay box and data from the antenna is continuously
received, every 128ms. The relay box has three potential free relay contact outputs which
are controlled by Limit 1 and Limit 2 for braking and stopping the crane movement. One
output relay is used for internal fault monitoring. The relays are held active by the
electronics and any exceeded limit or alarm of the function will make them trigger. Settings
and readout of parameters are easily accessible via a display and push buttons in the relay
box.
The internal fault monitoring is performed continuously. If the opposite unit has been turned
off or has a power failure, the modulated reflection remains active. This is because each
antenna has a backup receiver (rechargeable supercapacitor) for the modulating fingerprint
reflection and will continue to work for about 6-12 hours (depending on the temperature).
When the backup receiver has unloaded in a unit, the opposite unit still senses a signal from
the beam or other metal parts of the crane, which triggers an alarm to stop the movement
of the crane. For correct detection of this function, it is necessary to have a surface of metal
with minimum 1 m² behind the antennas.
GIGASENSE II contains a Microwave transmitter. Although it has very low output power, this
system must conform to the local regulations set up by the Telecom Authority in the user
country. This equipment operates in the 9.9
- 10.6 GHz frequency bands. See appendix 1 for
detailed information.
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