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ADDENDUM FOR "SURGE PROTECTION" OPTION OF THE TRANSMITTERS
GENERAL DESCRIPTION
This option provides a built-in surge protection circuit.
The surge protector is designed to dissipate large quantities of electrical energy which have been induced in a transmission line.
The option is suitable to protect up to 2500 V (5 kA discharge current) of 8µs rise time/20µs decay to half value.
These large quantities of energy can be induced in the signal transmission line by lightning discharge in the area or by nearby
electrical equipment.
The dissipation of this energy prevents damage to transmitter circuitry connected to the transmission line.
The surge protector will not protect the instrument in case of a direct lightning strike.
The surge protector board is located inside the terminal block of the transmitter (see drawing).
The circuit is designed to operate and recover automatically. It does not require periodic testing or adjustment.
FITTING PROCEDURE
(In case of traditional terminal block with two terminal for connection. See Fig. 1)
CAUTION : This procedure should not be carried out on the field site.
a)
Remove the transmitter cover of the field connections side.
b)
Unplug the built-in indicator, if present.
c)
Unscrew the two Phillips screws (M 4 x 18 mm) which secure the terminal block and pull it off the housing.
d)
Unscrew the two Phillips screws (M 3 x 6 mm) which fix the wire eyelet terminals of the two RF (radio frequency) filters, on
the back of the terminal block. Retain the screws.
e)
Fit properly the surge protector p.c. board and secure it by a self-tapping screw (M 2.9 x 6mm)
f)
Secure the two +/- eyelet terminals to +/- threaded holes on the back of the terminal block, by the two Phillips screws (M
3 x 6 mm) previously removed.
g)
Secure the two +/- wire eyelet terminals of the RF filters to the +/- threaded bushes of the p.c. board by two Phillips screws
(M 3 x 6 mm).
h)
Connect the wire eyelet terminal of the Surge Protector to the dedicated ground connection below terminal block, using a
provided self tapping screw M4x8 mm and relevant washers.
i)
Reinstall the terminal block and stick on the notice label in the proper position.
l)
Plug the built-in indicator, if used.
m) Refit the cover.
WARNING
The Surge Protector must not be used in I.S. and Type N european certified transmitters.
NOTE
The Surge Protector is suitably provided with the necessary installation screws and the notice label.
Adding the unit to an existing transmitter will affect the power supply requirement for a minimum added operating
voltage of 1.6 V d.c.
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