DayTronic IL70A Manuale - Pagina 12

Sfoglia online o scarica il pdf Manuale per Unità di controllo DayTronic IL70A. DayTronic IL70A 15. In-line dc strain gage conditioner

4. VERIFICATION OF NORMAL OPERATION

It is the purpose of this section to aid the user in determining, in the event of a malfunction

of which the Model IL70A is suspected of contributing, whether the instrument is

functioning normally or whether it is the source of the observed trouble. In the

event the unit requires repair, the user may also contact the factory Service

Department or the local Daytronic Representative for assistance. Daytronic service

information is located on the last page of this document.

If the instrument is suspected of faulty operation, perform the following steps.

If the unit is totally inoperational (front-panel power indicator does not light),

(a)

check the primary power input terminals for proper connection. Input power can

be from 11 to 28 Vdc and will draw less than 2 watts. If properly connected,

the front panel Green LED will be illuminated. Before reapplying power, visually

inspect the power supply and the input power connections for any discrepancy

which could have caused the overload.

If the transducer has some preloading, the BALANCE controls may not allow successful

(b)

zeroing of the instrument output. This condition can be remedied by connecting a

resistor (50 k- 200 k range, metal-film type) from the +Signal terminal of the

transducer to the + or –Excitation Sense terminals. The Excitation terminal to

which the connection is made is determined by the direction of the loading or off-

zero reading.

The inability to balance correctly, where the instrument output readstotally off scale

(c)

and the BALANCE controls have no authority, can very likely be the result of a

damaged or defective transducer or cable. This possibility can be confirmed (or

eliminated) by substituting a transducer and cable known to be in good condition or

by simulating a balanced transducer, using either a commercially available

transducer simulator or the simple star bridge arrangement shown in Figure 7. The star

bridge simulates a conventional four-arm bridge in an exact condition of bal-ance.

To construct a star bridge, connect four 10% carbon resistors as shown in Figure 5.

Use 180-ohm resistors to simulate a 350-ohm bridge and use 56-ohm resistors to

simulate a 120-ohm bridge. Neither the resistor values nor temperature

characteristics are critical since the balance condition of a star bridge is not

determined by the resistance values. Solder two resistors together, then solder

the remaining two resistors together. Next, connect the two junctions together

using a separate wire as shown. There is a good reason for this method of

construction, and it should be followed. Connect the substitute or simulated

transducer to the instrument I/O connector using a short 4-wire cable configuration as

shown in Figure 4. Attempt to balance the substitute simulated transducer. If

conditions now appear to be normal, the transducer or cable is at fault. If the

previous difficulties persist, the IL70A may be faulty.

DC Strain Gage Conditoner Module

IL70A