Emerson Transmitter 350 Mode D’Emploi

2. Water damage to the electronics module or

sensor probe. This is potentially the most

severe case the symptoms are unpredictable. If

there is any suspicion that the transmitter may

have incurred water damage please contact the

factory to make arrangements to have the unit

sent back for factory inspection.

Physical and water damage are not

covered under warranty.

3. Magnetic Indentation. It is possible for any

magnetostrictive instrument to have residual

magnetic energy stored along the length of the

waveguide. These magnetic anomalies can

interfere with the output response signal. If

this appears to be the case a level gage float (or

a bar magnet preferably) may be run along the

length of the sensor tube, past the head of the

transmitter, in an even motion without

stopping. This will usually clear all such

magnetic anomalies.

Never move a magnet in perpendicular

motion away from the sensor tube. This will

always leave a residual magnetic field in the

waveguide which causes the transmitter

output to be erroneous or unstable.

The LTM-350 is HART compatible, however

HART communication will not work if the unit

is not powering up.

8.2 Power Supply Troubleshooting

The LTM-250/350 is designed to operate with a

supply voltage of 13 – 36 Vdc (minimum 13V @

20mA) across its terminal without affecting the

analog current output. The most common supply

voltage used is 24Vdc.

At times additional resistance in the loop is

necessary, either in the form of a second load

resistor or higher resistance safety barrier. This will

appear to limit the maximum output of the

transmitter to below 20mA. The transmitter will

perform correctly up to a certain point. To resolve

this problem, the voltage of the loop supply must

be increased. Even a slight adjustment of 1Vdc may

be sufficient.

All connections must be checked for improper

wiring or polarity before power is applied. LTM-

Series transmitters are polarity protected.

8.3 General Troubleshooting

Below are some troubleshooting procedures for the

LTM transmitters that have been established

overtime.

Symptom: Transmitter is not powering up.

The LCD is not turning on.

Resolutions:

1. Make sure power is applied correctly (meaning

plus and minus are not reversed). The

transmitter is polarity protected.

2. Make sure the electronics module is seated

properly. Open the front cover (where the LCD

is) and firmly push on the “Magtech” text. A

good way to tell if the electronics are not

seated properly is by making sure the

protection screws are not physically higher than

the outside of the housing. Sometimes pulling

the electronics module out and putting it back

in can reseat the electronics correctly. Use

cutters or needle nose pliers to grip the

protection screw and lightly pull on each screw

(alternate).