DayTronic IL78A User Manual

1 GENERAL DESCRIPTION AND SPECIFICATIONS

AC Strain Gage

C

ONDITIONER Module

IL78A

IN-LINE AC Strain Gage Conditioner

MODEL IL78A

The Model IL78A is a single-channel conditioner of phase-sensitive carrier-amplifier design.
Intended for applications involving transformer-coupling to the transducer bridge (as with rotary­transformer torque sensors), this conditioner can also be used in conventional installations when
high sensitivity is required or where the electrical envi
only to the modulated carrier frequency, the IL78A rejects extraneous voltages that can cause
errors in DC systems, particularly when there is a need to “blow up” a portion of the transducer
range. User-adjustable phase and symmetry controls are provided.

The Model IL78A's is calibrated by means of a “two-point (dead-weight)” or shunt-calibration

technique, which are outlined in section three. The user can utilize the shunt calibration method
by adding the correct leaded shunt resistor value from "Cal Sense" to either + Sense or - Sense
depending on the polarity desired.

ronment is especially noisy. Responding

Top View of the Model IL78A AC Strain Gage Module (cover removed)

Shunt Operation: Located between the two screw terminal connectors, t

selection. "EXT" is for an external - user installed shunt or
enables the selected feature. For an external shunt resistor, install the leaded resistor between the "Cal Sense" (pin 7) terminal
and either the + Signal (pin 5) or the - Signal (pin 6) terminals. Use the SW4 "Shunt" button to engage the shunt resistor across
the selected side of the bridge or "SHP or "SHN" logic input lines. For transducers with an installed shunt resistor, place the
jumper on the "EXT" teminals and wire the "Cal Sense" line to the transducer's shunt connector pin.

"INT" for the internal - built in - 59K Ohm shunt. Installing the jumper

he IL70A contains a Shunt resistor jumper

AC Strain Gage Phase Operation

Due to the AC modulated aspects of the IL78A AC Voltage excitation circuit, the IL78A8 contains a "PHASE"
adjustment whi
demodulator is aligned properly through calibration, maximum amplitude and linearity are achieved.

92371.00 rev. B

ch aligns the transducer's return output signal to the conditioner's demodulator. When the

GENERAL DESCRIPTION AND SPECIFICATIONS IL78A.1

WARNING

Death, serious injury, or fire

hazard could result from improper connection of this instrument. Read and understand this

manual before connecting this instrument. Follow all installation and operating instructions while using this instrument.

Connection of this instrument must be performed in compliance with the National Electrical Code (ANSI/NFPA 70-2014) of
USA

and any additional safety requirements applicable to your installation.

Installation, operation, and maintenance o

f this instrument must be performed by qualified personnel only. The National
Electrical Code defines a qualified person as “one who has demonstrated the skills and knowledge related to the construction
and operation of the electrical equipment and installations, and who has received safety training on the hazards involved.”

Qualified personnel who work on or near exposed energized electrical conductors must follow applicable safety related
work

practices and procedures including appropriate personal protective equipment in compliance with the Standard for
Electrical Safety Requirements for Employee Workplaces (ANSI/NFPA 70E-2012) of USA and any additional workplace safety
requirements applicable to your installation.

ADVERTENCIA

Una conexión incorrecta de este instrumento puede producir la muerte, lesiones graves y riesgo de incendio. Lea y entienda
este manual antes de conectar. Observe todas las instrucciones de instalación y operación durante el uso

de este

instrumento.

La conexión de este instrumento a un sistema eléctrico se debe realizar

en conformidad con el Código Eléctrico Nacional
(ANSI/NFPA 70-2014) de los E.E.U.U., además de cualquier otra norma de seguridad correspondiente a su
establecimiento.

La instalación, operación y mantenimiento de este instrumento debe ser realizada por personal calificado solamente. El
Código Eléctrico N

acional define a una persona calificada como "una que esté familiarizada con la construcción y operación del

equipo y con los riesgos involucrados."

El personal cualificado que trabaja encendido o acerca a los conductores eléctricos energizados expuestos debe seguir
prácticas y procedimientos relacionados seguridad aplicable del trabajo

incluyendo el equipo protector personal apropiado
en conformidad con el estándar para los requisitos de seguridad eléctricos para los lugares de trabajo del empleado (ANSI/
NFPA 70E-2012) de los E.E.U.U. y cualquier requisito de seguridad adicional del lugar de trabajo aplicable a su instalación.

AVERTISSEMENT

Si l'instrument est mal connecté, la mort, des blessures graves, ou un danger d'incendie peuvent s'en suivre. Lisez
attentivement ce manuel avant de connecter

l'instrument. Lorsque vous utilisez l'instrument, suivez toutes les

instructions d'installation et de service.

Cet instrument doit être connecté conformément

au National Electrical Code (ANSI/NFPA 70-2014) des Etats-Unis et à

toutes les exigences de sécurité applicables à votre installation.

Cet instrument doit être installé, utilisé et entretenu uniquement par un personnel qualifié. Selon le National Electrical
Code, une personne

est qualifiée si "elle connaît bien la construction et l'utilisation de l'équipement, ainsi que les dangers

que cela implique".

Le personnel qualifié qui travaillent dessus ou s'approchent des conducteurs électriques activés exposés doit suivre des
pratiques en ma

tière et des procédures reliées par sûreté applicable de travail comprenant le matériel de protection
personnel approprié conformément à la norme pour des conditions de sûreté électriques pour les lieux de travail des
employés (ANSI/NFPA 70E-2012) des Etats-Unis et toutes les conditions de sûreté additionnelles de lieu de travail
applicables à votre installation.

WARNUNG

Der falsche Anschluß dieses Gerätes kann Tod, schwere Verletzungen oder Feuer verursachen. Bevor Sie dieses Instrument
anschließen, müssen Sie die Anleitung lesen und verstanden haben. Bei der Verwendung dieses Instruments müssen alle
Installation- und Betriebsanweisungen beachtet werden.

Der Anschluß dieses Instruments muß in Übereinstimmung mit den nationalen Bestimmungen für Elektrizität (ANSI/NFPA
70- 2014
werden.

) der Vereinigten Staaten, sowie allen weiteren, in Ihrem Fall anwendbaren Sicherheitsbestimmungen, vorgenommen

Installation, Betrieb und Wartung dieses
Bestimmungen für Elektrizität wird ein Fachmann als eine Person bezeichnet, welche "mit der Bauweise und dem Betrieb des
Gerätes sowie den dazugehörigen Gefahren vertraut ist."

Qualifiziertes Personal, das an bearbeiten oder herausgestellte angezogene elektrische Leiter sich nähern, muß anwendbare
Sicherhe
Standard für elektrische Sicherheitsauflagen für Angestellt-Arbeitsplätze (ANSI/NFPA 70E-2012) der Vereinigten Staaten
und alle zusätzlichen Arbeitsplatzsicherheitsauflagen folgen, die auf Ihre Installation anwendbar sind.

it bezogener Arbeit Praxis und Verfahren einschließlich passende persönliche schützende Ausrüstung gemäß dem

Instruments dürfen nur von Fachpersonal durchgeführt werden. In dem nationalen

Safety Precautions

The following safety precautions must be followed whenever any type of voltage or current connection is being made to the
instrument.

o Before connecting to electric circuits or pulse initiating equipment, open their related breakers or disconnects. It is

recommended NOT TO install any connection of the instrument on live power lines. Only Qualified Service personnel that
have demonstrated the abilities and received the proper safety training are capable of connecting to live circuits.

o Connections must be made to the instrument first, then connect to the circuit to be monitored.

o Wear proper personal protective equipment, including safety glasses and insulated gloves when making connections to

power circuits.

o Hands, shoes and floor must be dry when making any connection to a power line.

o Before each use, inspect all cables for breaks or cracks in the insulation. Replace immediately if defective.

o If the equipment is used in a manner not specified in this user’s guide, the protection provided by the equipment may be

impaired.

Medidas de seguridad

Las medidas de seguridad siguientes deberá

n observarse cuando se realice c

ualquier tipo

de

conexión al instrumento.

ο Cuando se haga conexiones a circuitos eléctricos o a equipo de

de seguridad. NO deberá hacerse ninguna conexión del instrumento en líneas eléctricas bajo tensión.

ο Las conexiones deberán hacerse primero al instrumento y, luego, al circuito a ser monitorizado.

ο Al hace

ο Sus ma

ο Verifique que la unidad esté DESACTIVADA antes de conectar sondas en el panel posterior.

ο Previo a cada uso, deberá verificarse que los cables no estén rotos y que el

r conexiones a circuitos eléctricos, deberá utilizar anteojos y guantes protectores.

nos, zapatos y el piso deberán estar secos en

Reemplace de inmediato cualquier parte defectuosa.

todo momento en que se haga una conexión a un cable eléctrico.

activación por pulso, deberá abrirse sus respectivas cajas

material aislante no tenga rajaduras.

Mesures de Sécurité

Les mesures de sécurité suivantes doivent être prises chaque fois qu’un type de connexion quelconque est effectué
sur l’instrument.

ο Ouvrir les disjoncteurs correspondants lors d’une connexion à des circuits électriques ou à des équipement de génération

d’impulsions. NE PAS effectuer de connexion d’instrument sur des lignes électriques sous

ο Une fois toutes les connexions de l’instrument effectuées, connecter au circuit à contrôler.

tension.

ο Porter des lunettes de protection et des gants isolants pour effect

ο S’assure

ο S’assurer que l’unité est ÉTEINTE avant de connecter les sondes au panneau arrière.

ο Inspecter tous les câbles, avant chaque utilisation, pour s’assurer que les isolants ne sont pas coupés ou fendus.

r que les mains, les

Remplacer immédiatement tous les équipements défectueux.

chaussures et le sol soient secs lors de connexions à une ligne électrique.

uer des connexions aux circuits électriques.

Sicherheitsvorkehrungen

Die folgenden Sicherheitsvorkehrungen sind immer dann zu befolgen, wenn eine Verbindung zum Instrument hergestellt wird.

ο Öffnen Sie beim Anschl

Unterbrecher. Es dürfen KEINE Anschlüsse an das Instrument unter stromführenden Spannungsleitungen montiert
werden.

ο Die Verbindungen müssen zuerst am Instrument und danach an der zu überwachenden Schaltung hergestellt werden.

ο Tragen Sie Schutzbrillen und Isolierhandschuhe, wenn Sie Anschlüsse an den Stromkreisen vornehmen.

ο Hände, Schuhe und Fußboden müssen trocken sein, wenn Sie Anschlüsse an den Stromkreisen durchführen.

ο Stellen Sie sicher, daß das Gerät AUSgeschaltet ist, bevor Sie an der rückwärtigen Konsole Meßfühler anschließen.

ο Prüfen Sie vor jedem Gebrauch alle Kabel auf Bruchstellen und Risse in der Isolierung. Wechseln Sie schadhafte Kabel

sofort aus.

uß an elektrische Stromkreise oder Impulsauslösungseinrichtungen die entsprechenden

Standard Accessories

Standard
accessories

The following table lists the IL & ILA standard accessories.

Description Part Number

Manual & Operating instruction

Resource CD

AC Strain Gage Conditioner

Module IL78A

IL78A SPECIFICATIONS

Measurement Range: Adjustable 0.5 mV/V to 5.0 mV/V; nominal full-scale
Transducer Types:

coupled - 120 to 10 k ohm

Excita

Power Supply
Analog Ouput: selectable; ± 0 to 5, ± 0 to 10 Vdc, 4-12-20 or 4-20mA (20% over-range, voltage only)

Operating Temperature
Amplifier

tion: 3.28 kHz; Nominal 2.77 Vac rms, sensed

Normal - Mode Range : ±1.5 V rms operating; ± 8 V without instrument damage

Input Impedance : Differential > 10 MΩ
Offset : vs. Temperature: ±30 ppm

Gain Accuracy

Gain Stability

Linearity

Filter

: 3-pole modified Butterworth; 3 dB down at 10 Hz, 100 Hz or 650 Hz; selectable

Step-Response Settling Time (Full-Scale Output @ 10 Hz:)

To 1% of final value: 0.08 sec; (0.008 sec @ 100 Hz) (0.0011 sec @ 650 Hz)
To 0.1% of final value: 0.095 sec; (0.0095 sec @ 100 Hz) (0.0016 sec @ 650 Hz)
To 0.02% of final value: 0.10 sec; (0.01 sec @ 100 Hz) (0.0014 sec @ 650 Hz)

: better than ± 0.03% of full scale

Conventional 4-arm strain gage bridges, typically transformer

: 11 - 28 Vdc regulated; 100 mA max.

: -10 to +70 Degrees C, 5 to 95% relative humidity, non-condensing

µV/°C; vs. Time: ±10 ppm/month

Limited only by calibration accuracy

:

: vs. Temperature: ±30 ppm/°C; vs. Time: ±10 ppm/month

Dimensions

GENERAL DESCRIPTION AND SPECIFICAT

IONS IL78A.1

2 TRANSDUCER CONNECTIONS

AC Strain Gage Conditioner Module IL78A

The Model IL78A I/O CONNECTIONS are via non-removable screw terminals which will accept wire
sizes from AWG 16 to 30. NOTE: The recommended transducer cabling would be eight wire,
individually shielded, twisted pair - wired as indicated (Fig. 1) Sense lines must be connected at the
transducer (as re
screw terminal assignments

commended) or at the IL78A screw terminals - as a minimum. Table 2 denotes

Table 2 Model IL78A Pin Assignments

I/O Connector

Terminal

1
2

Fig. 1 Model IL78A Transducer Cabling

J1

J2

3
4
5
6
7
8

1
2
3
4
5
6
7
8

Terminal

Label

Analog Output
SHP
SHN

Sync
Analog Common
Power Common
+ 24 Vdc
Shield

+Excitation
+ Sense

- Excitation

- Sense

+ Signal

- Signal

Cal Sense

Shield

Conditioner

LineScrew

Function

+ Signal Output

Shunt positive switch input
Shunt negative swithc input

Master / Slave Sync I/O

- Signal Output
Power Supply Common
11 - 28 Vdc Input Power
Earth ground

+ Sensor Power
+ Sensor Power Sense

- Sensor Power

- Sensor Power Sense

+ Signal from Sensor

- Signal from Sensor

Calibration Shunt Sense

Earth ground

7 Wire confirguration (recommended)

4 twisted pair, shielded wire be used.

Paired as follows:

+ & - Excitation
+ & - Sense
+ & - Signal
Cal Sense and unused wire
Shield at the instrument only

4 Wire confirguration

2 twisted pair, shielded wire be used.

Paired as follows:

+ & - Excitation
+ & - Signal
Shield at the instument only

Sense lines must be connected at the
instrument

TRANSDUCER CONNECTIONS IL78A.2

AC Strain Gage Conditioner Module IL78A

Shunt Resistor Selection

The IL78A has a Internal and External shunt
selection jumper located between the two wiring
connectors. Below are the appropriate wiring and
jumper selections depending on the application
using the recommended 7 wire configuration.

When more than one IL78A is being used in the same measurment setup, beat frequencies can be produced by
the excitation clock oscillator. To prevent this,
switch 6 on the front panel. The other units should be switched to Slave and wired as shown with the SYC
terminals connected and a separate Power Common wire.
Power com terminal should be connected at the modules.

the user should declare one of the IL78A units as a Master via

If the units share a common power supply, the

Fig. 2 Master / Slave Wiring

TRANSDUCER CONNECTIONS IL78A.2

Fig. 4 Remote Shunt Activation Connections

TRANSDUCER CONNECTIONS IL78A.2

AC Strain Gage Conditioner Module IL78A

3 GENERAL DESCRIPTION AND CALIBRATION

The Model IL78A is useful in applications involving tranformer coupling to the strain gage bridge (for example,
rotary transformer torque sensors) and in certain appications that require high

sensitivity with optimum signal-to­noise characteristics. Carrier amplifiers offer higher sensitivity than dc amplifiers and, since they respond only to
the modulated carrier frequency, they reject certain extraneous voltages that can cause error in dc systems. These
error sources include thermocouple or galvanic voltages in the cable-connector system, homopolar voltages from
rotating machinery, low-frequency pickup, and 1/f noises of various origin.

Calibration of the IL78A is accomplished by the conventional shunt technique, using an internally (or
externally) installed calibration resistor, or via the "de

ad-weight" method.

Calibration Resistor. If a fixed resistor is shunted across one arm of a strain gage bridge, it produces an unbalance
equivalent to that of a particular value of mechanical input. If this Equivalent Input value is accurately known, it can
be used as a reference point for shunt calibration of the system. Upon completion of installation of the transducer
and its associated cabling, the user can:

Perform an overall dead weight calibration using a precisely known value
of mechanical input. The calibration can

then be transferred to the installed

calibration resistor for convenience in subsequent checking.

Install an external calibration resistor with one (or an equivalent resistance value)
supplied by the transducer manufacturer to achieve a precisely known Equivalent

Input allowing the instrument sensitivity to be adjusted correctly. Move jumper
from INT to the ETX terminals, install resistor between Cal Sense and + or - Signal.

Determine the Equivalent Input value for the installed calibration resistor (59K),

knowing the transducer sensitivity, and adjust the instrument sensitivity accordingly.

Jumper to be in the INT location.

A one percent 59-kilohm calibration resistor is installed in the IL78A at the factory. The installed
resistor can usually be used even though the transducer calibration data mentions some
other resistance value. In Section 4 of this manual, the techniques described above are
demonstrated. If, however, the installed value of the calibration resistor is not appropriate
for the transducer and measurement range to be used, the 59-kilohm resistor should be

disabled by placing the Shunt jumper in the "EXT" position and an external shunt resistor
should be used.

Note: A variety of Rotary Transformer Torque Transducers are supplied with the appropriate
calibration resistor integral to the transducer. When this type of transducer is used it will be
necessary to move the Shunt jumper to the EXT position and connect the CAL Sense wire
to the shunt activation pin of the transducer. Refer to Fig 1 cabling diagram section of this
manual in the area of CAL SENSE.

(1)

(2)

(3)

Calibration IL78A.3

AC Strain Gage Conditioner Module IL78A

3. CALIBRATION (cont.)

This section contains the instructions for calibrating the IL78A. Included is a functional description of
the

instrument front-panel (see Figure 2). To perform calibration, proceed as follows.

Turn power ON to the IL78A DC Power input terminal (11 to 28 Vdc input) The
front-panel indicator should light green to indicate the application of dc power.
Allow 10 minutes of warmup for stabilization of transducer characteristics.
Remove the top cover of the unit to make the proper connections and adjustments.

Set the Coarse Zero control to position 8 and the Coarse Span control to position 0.

Position the front panel switches to the desired settings for the application. Refer
to Figure 2 for details. If using Shunt method, refer to step (k).

(b)

(a)

(c)

With the transducer unloaded, adjust the Coarse Zero control and the Fine Zero control until
the desired analog output is achieved. If greater zero authority is desired, place the front panel
Switch 7 - "Zero Adj" to the extended range. This will allow the user to obtain 100% zero offset
control. The Normal postion of switch 7 allows for approximately 25% Zero authority.

(d)

Load the transducer in the positive direction with a convenient dead weight value (greater than one

half of full scale). Adjust Coarse Span for a nominal corresponding output. Adjust the PHASE control,

until a maximum output value is obtained. (Once set for your transducer, this PHASE ADJUSTMENT

step need not be repeated unless a change in cable length – or transducer – is required). Unload the

sensor and re-Zero as needed.

(e)

(f)

If the calibration will utilized a known "dead-weight", re-load the sensor and adjust the Coarse and

Fine Span controls for the expected analog output value. Unload - Zero and Load - Span operations
may need to be repeated for analog output precision.
Note: With sensor unloaded, activate & record "SHP" value for furture calibration verification.

If the calibration will utilize the "Shunt" calibration method, refer to step (k).

(g)

If the transducer is to be also used in the negative realm, load the transducer in
the negative direction with the same dead weight value as used in step (f) and confirm
that the dead weight reading obtained is the same, but negative polarity, as that of step
(f). If not, see steps (i) thru (j).

A Symmetry adjustment is provided to compensate for transducers that do not have
symmetrical sensitivity characteristics. This adjustment is factory set assuming
symmetrical characteristics. If step (h) indicates that a field adjustment is necessary,
proceed as follows.

(h)

(i)

Calibration IL78A.3

AC Strain Gage Conditioner Module IL78A

With the transducer loaded as in step (f), adjust the Symmetry control (right above the PHASE
control adjustment) to obtain a dead weight reading equal to that obtained in step (f).

If dead weight calibration is not practical and the transducer manufacturer has supplied a
calibration resistor (or resistor value), install the recommended calibration resistor. See
Fig. 5

(j)

(k)

Perfom steps (b) thru (e). Now activate the SHUNT POSITIVE (SHP) terminal
and adjust the SPAN controls until the instrument output is equal to the Equivalent Input
value simulated by the installed resistor. Shunt is performed at zero load.

If a negative Equivalent Input value is also provided on the calibration sheet of the transducer
under calibration, activate the SHUNT NEGATIVE (SHN) terminal. Confirm that the negative
value can also be obtained. If necessary, adust the SYMMETRY control to obtain the negative
Equivalent Input value as listed on the calibration document. The SYMMETRY control has
approximately 7% authority, full scale.

If dead weight calibration is not practical and the transducer calibration data is unknown,
the Equivalent Input value for the factory-installed calibration resistor can be
approximated as follows, assuming that the mv/v sensitivity rating of the transducer
and the bridge resistance are known.

(l)

(m)

where X = Equivalent Input, % of full scale

Rb = bridge resistance, ohms

K = transducer sensitivity, mV/V full scale

Rc = calibration resistance, ohms (59 k installed)

Sample Calculation: Assume that K = 3.000 mV/V for a 5000-pound load cell

(fullscale) with a bridge resistance of 350 ohms.

49.4% of full scale = 2472 pounds

X =

25000 R

b

K R

c

X =

59000 x 3

25000 x 350

=

3. CALIBRATION (cont.)

Note: Above calculation is useful in applications involving non - star bridge shunt calibration strain gage bridges (for
example DC bridges, and slip ring type torque sensors). Rotary transforme

r type sensors which use star bridge shunt

circuit will not equate properly and the sensor's published calibration data should be referenced.

Calibration IL78A.3

AC Strain Gage Conditioner Module IL78A

Remote Calibration Check: The instrument can be placed in the calibration mode (positive or negative) by

shorting terminals Power Common and SHP for positive or SHN for negative on the lower I/O connector.
Figure 4 indicates two methods of remotely entering the calibration mode (external switch, or push
button control). The Remote Cal function provides a

convenient method of periodically monitoring

calibration

of

the

instrument

in

the

positive

or negative realm.

Master/Slave Connections. : When more than one IL78A is being used in a measurement setup
(instruments are closely mounted or the transducer cabling is in a common conduit or raceway),
beat frequencies may be produced from the 3-kHz oscillators used in the instruments to develop the
excitation. To prevent beat frequencies from occur-ring, one unit can be designated the master, and
the remaining units can be driven from the oscillator contained in the master unit. The remaining
units are designated as slave instruments. To perform master/slave wiring, refer to Figure 7.

3. CALIBRATION (cont.)

Sw

itch 1 - Mo

de - current (I) or voltage analog output

Switch 2 - Volts - +/- 5 or +/-

10 Vdc when mode is voltage

Switch 3 - Current - 4-12-20 or 4-20mA when mode is current
Switch 4 - Filter - 650 Hz or 100 Hz at 3 db, for 100 Hz switch 5 must be set down
Switch 5 - Filter - 10 Hz or 100 Hz at 3 db, for 100 Hz switch 4 must be set down
Switch 6 - Sync - excitaton clock to slave from a master module or to be master
Switch 7 - Zero Adj. - extended (100%) or normal (25%) zero authority
Switch 8 - Aux Output - SYC terminal output for use by other modules

Coarse Zero - 16 position switch adjustment for stepped zero

balance control marked for calibration default position

Fine Zero - 18 turn potentiometer for fine zero balance control

Coarse Span - 16 position switch adjustment for stepped gain

contr ol marked for calibration default position

Fin

e Span - 18 turn potentiometer for fine gain - span contr

ol

Symmetry - adjust the negative output span to be equal

to the positive output

Phase - adjustment for phasing the AC modulated signal to its

highest level at load

Over Range - indicates when the analog output is 2% greater

tha

n mode selected

Power - indicates the power input voltage is ON

Fig. 2 Front Panel Settings and Indicators

Calibration IL78A.3

AC Strain Gage Conditioner Module IL78A

4. VERIFICATION OF NORMAL OPERATION

It is the purpose of this section to aid the user in determining, in the event of a malfunction
to which the Model IL78A 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, follow the steps below.

(a)

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

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.

(b)

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

(c)

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

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

balance. 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 IL78A is faulty.

Verification of Operation IL78A.3

AC Strain Gage Conditioner

Module IL78A

AC Strain Gage Conditioner Module IL78A

Fig. 4 Star Bridge

Daytronic CorporationDayton OH USA

wwwwww..ddaayyttrroonniicc..ccoomm

AC Strain Gage Conditioner Module IL78A

Product Warranty and Repair

Daytronic Corporation warrants its products to be free from defects in material and
workmanship, under normal and proper use in accordance with our instructions,
for the period of time specified below. Our liability under such warranty or in
connection with any other claim relating to the products shall be limited to, at our
option, the repair or replacement of any products or parts or components thereof
which are returned to us freight prepaid and which are defective in material or
workmanship or the refund of the purchase price to the Buyer.

ANY PRODUCT FOUND TO BE DAMAGED THROUGH CUSTOMER NEGLIGENCE OR MIS­USE MAY BE EXCLUDED FROM ANY AND ALL POLICIES CONTAINED IN THIS DOCUMENT.

ALL EQUIPMENT TO BE REPAIRED OR REPLACED UNDER WARRANTY MUST BE
RETURNED TO THE FACTORY.
customer must call Daytronic Customer Support Services at

RETURN MATERIAL AUTHORIZATION (RMA)

necessary information and has been assigned a specific RMA, the product(s) in question
may be returned to Daytronic by shipping it

Before returning a product or products for any reason, the

[phone] to request a

. Once the customer has provided the

Daytronic Corp. , 1000 New Durham Road, Edison, New Jersey 08818

Daytronic Customer Service: 1-800-668-4745 [e-mail]