10A73-4 - Unspecified Daytronic - Free user manual and instructions

USER MANUAL 10A73-4 Daytronic

Intended primarily for stress analysis applications, the Model 10A73-4 receives and conditions up to four independent inputs from one-arm (1/4-bridge), two-arm (1/2-bridge), and four-arm (full-bridge) strain gage configurations attached directly to the stressed material.

If you are measuring strain by means of a one-arm (1/4-bridge) strain gage configuration, BE SURE TO STUDY SECTION 4 FOR A DISCUSSION OF "LEAD WIRE AND NONLINEARITY EFFECTS WITH QUARTER-BRIDGE STRAIN GAGE CONFIGURATION."

Unless all four inputs originate from full-bridge transducers, the 10A73-4 requires external completion of each strain gage input to full bridge, by means of one of the following:

- a System 10 Bridge Completion Connector—one of the following models:

— 10QBC-4-120 for 2- or 3-wire 120-Ω quarter-bridge connections
— 10QBC-4-350 for 2- or 3-wire 350-Ω quarter-bridge connections
— 10QBC-4-1K for 2- or 3-wire1000-Ω quarter-bridge connections
— 10HBC-4 for 4- or 6-wire half-bridge connections
— 10FBC-4 for 5-wire full-bridge connections

• a Daytronic Model 10CJB-4 Quad Bridge Completion Card (described in Section 2.b) ^1 ;
  • equivalent circuitry supplied by the user ^2

When the 10A73-4 is used with one of the System 10 Bridge Completion Connectors listed above, the excitation level is fixed at 5 V-DC. In the absence of a Bridge Completion Connector—whether or not the Model 10CJB-4 is used—the 10A73-4 provides selectable low-level excitation (1, 2, or 5 V-DC) to help reduce gage heating effects in materials with low thermal conductivity. ^3 However, the selection of excitation level for the 10A73-4 is not “per channel”; the same level applies to all four 10A73-4 channels. See Section 3.a for details.

As explained in Section 3.b, the 10A73-4 can be quickly calibrated either through "calculated" calibration—involving application of the MVV command—or through a convenient shunt technique. Unless a System 10 Bridge Completion Connector is being used with the 10A73-4, all four shunt resistors may be switched in and out simultaneously by means of logic-level inputs through the rear I/O CONNECTOR.

ADDITIONAL 10A73-4 SPECIFICATIONS

Transducer Types: 1-arm (1/4-bridge), 2-arm (1/2-bridge), or 4-arm (full-bridge) strain-gage configurations. 2-wire or 3-wire 1/4-bridge configurations may use either 120 Ω, 350 Ω, or 1 kΩ nominal gage resistance; full-bridge configurations should use 350-Ω gages (or higher) or should use 120-Ω gages with either 1-V or 2-V excitation. Unless all four inputs originate from full-bridge transducers, the Model 10A73-4 requires either an appropriate System 10 Bridge Completion Connector; a Model 10CJB-4 Quad Bridge Completion Card; or equivalent bridge-completion circuitry supplied by the user.

Transducer Ranges: ±0.750, 1.500, or 3.000 mV/V; for System 10 channel "type" codes assigned to 10A73-4 data channels, see Table 1

Excitation (for all four channels): Sensed excitation selectable 1, 2, or 5 V-DC (i.e., ±0.5, ±1, or ±2.5 V-DC, respectively), nominal

Amplifier (per channel):

Common-Mode Range: ±0.4 V operating; ±5 V without instrument damage

Common-Mode Rejection Ratio: DC: -90 dB; at 60 Hz, 1 kHz, and 3 kHz: -120 dB

Input Impedance: Differential: greater than 100 MΩ; Common-Mode: greater than 100 MΩ

Offset: Initial: ±0.04% of full scale; vs. temperature: ±20 ppm/°C; vs. time: ±10 ppm/month

Gain Accuracy*: ±0.02% of full scale with 5-V excitation; ±0.02% of full scale with 1-V or 2-V excitation typical, following calibration

Gain Stability: vs. temperature: ±50 ppm/°C; vs. time: ±20 ppm/month

Filter: 3-pole modified Butterworth; 3 dB down at 10 Hz; 60 dB down at 100 Hz

Step-Response Settling Time (Full-Scale Output):

To 1% of final value: 100 msec

To 0.1% of final value: 150 msec

To 0.02% of final value: 600 msec

Auxiliary Output: Filtered outputs available on mainframe wire-wrap pins

Table 1 10A73-4 "Type" Codes

Full-Scale ChannelInput Type Code

0.750 mV/V 70

1.500 mV/V 71

3.000 mV/V 72

2 GAGE / TRANSDUCER CONNECTIONS

Table 2, below, gives pin assignments for the 10A73-4's rear I/O CONNECTOR, to which appropriate BRIDGE COMPLETION CIRCUITRY must be attached, unless all four inputs originate from full-bridge transducers.

Section 2.a describes the cabling to be used with System 10 Bridge Completion Connectors.

Section 2.b describes the cabling to be used with the Model 10CJB-4 Quad Bridge Completion Card.

Section 2.c describes the cabling to be used in the absence of bridge-completion circuitry (i.e., connection to four full-bridge transducers).

IMPORTANT: The ±EXCITATION, ±SENSE, and ±SIGNAL pins for an UNUSED STRAIN GAGE INPUT CHANNEL should be jumpered at the I/O CONNECTOR or in the BRIDGE COMPLETION CONNECTOR as shown in Fig. 1, below. If an input is left open, high-frequency oscillation can result, which can in turn produce significant interchannel crosstalk, and possibly inaccurate data readings.

ALSO NOTE: Logic connections for remote control of shunt calibration (using the I/O CONNECTOR'S "NOT ±CALIBRATE" pins) are discussed in Section 3.b and shown in Fig. 8. Note that these logic-level inputs are not available for use when a Bridge Completion Card is attached to the 10A73-4.

Table 2 Model 10A73-4 Pin Assignments

I/O Connector Conditioner Conditioner Pin Channel Line Number Number Function
1	1	+SIGNAL
A	1	-SIGNAL
2	1	C	AL SENSE
B	*	+EXCITATION
3	2	+SIGNAL
C	2	-SIGNAL
4	2	CAL SENSE
D	*		+SENSE
5	3	+SIGNAL
E	3	-SIGNAL
6	3	C	AL SENSE
F	*	-SENSE
7	4	+SIGNAL
H	4	-SIGNAL
8	4	CAL SENSE
J	*	-EXCITATION
9	*	NOT +CALIBRATE
K	*	EXC PROGRAMMING
10	*	NOT -CALIBRATE
L	*	POWER COMMON

graph TD
    A["Model 10A73-4 I/O Connector or Bridge Completion Card"] --> B["+ EX (All Chns.)"]
    A --> C["+ SEN (All Chns.)"]
    A --> D["-EX (All Chns.)"]
    A --> E["-SEN (All Chns.)"]
    A --> F["+ SIG (Chn. n)"]
    A --> G["-SIG (Chn. n)"]
    A --> H["PWR COM or SHIELD (All Chns.)"]
    B --> I["THESE JUMPERS ARE NEEDED IF AND ONLY IF III THE ENTIRE 10A73-4 CARD II IS INSTALLED BUT UNUSED."]
    C --> I
    D --> I
    E --> I
    F --> I
    G --> I
    H --> I

* This function is common to all four channels.

2.a 1/4-, 1/2-, OR FULL-BRIDGE GAGE CONNECTIONS USING A SYSTEM 10 BRIDGE COMPLETION CONNECTOR

Each System 10 Bridge Completion Connector attaches directly to the rear I/O CONNECTOR of the Model 10A73-4.

Remove the top plate of the connector. Inside are four sets of labelled screw terminals, corresponding to the 10A73-4's four input channels. You will connect your gage wires directly to these terminals and, if necessary, interconnect certain terminal pairs by means of jumper wires. All gage leads should be securely clamped by means of the two cable clamps.

Fig. 2 shows per-channel connections between external strain-gage configurations and the respective System 10 Bridge Completion Connectors.

NOTE: Unlike the Model 10CJB-4, the Bridge Completion Connectors DO NOT PERMIT MIXING OF CONNECTED GAGE CONFIGURATION TYPES. That is, all gage configurations connected to the same Bridge Completion Connector must be of the same appropriate type (e.g., 120-Ω 1/4-bridge, 1/2-bridge, etc.).

When input connections involve pairs of EXCITATION, SENSE, and/or SIGNAL lines, these should be twisted pairs within the input cable. While it is desirable to shield such pairs individually (as shown in Fig. 2), this is not necessary; an overall cable shield is acceptable.

Note too that the full-bridge input connections given in Fig. 2(e) are to be used if one or more of the 10A73-4's other inputs derives from a less than full-bridge configuration. If all four inputs originate from full-bridge configurations, no completion circuitry is required (see Section 2.c and Fig. 4).

Fig. 2 Model 10A73-4 Strain Gage Cabling Using System 10 Bridge Completion Connectors
Fig. 2(a) Per-Channel Connections to Model 10QBC-4* for 2-Wire 1/4-Bridge Completion

Per-Channel ons to Model for 2-Wire e Completion Model 10QBC-4 +EXC CAL SEN +SIGNAL -EXC SHIELD Signal Excitation

Fig. 2(b) Per-Channel Connections to Model 10QBC-4* for 3-Wire 1/4-Bridge Completion

Model 10QBC-4 +EXC CAL SEN +SIGNAL -EXC SHIELD Signal Excitation

* I.e., Model QBC-4-120, QBC-4-350, or QBC-4-1K.

Fig. 2(c) Per-Channel Connections to Model 10HBC-4 for 4-Wire 1/2-Bridge Completion

graph LR
    A["Signal"] -->|+Excitation| B["+EXC"]
    A -->|-Excitation| C["-SENSE"]
    B --> D["+SENSE"]
    C --> E["+SIGNAL"]
    D --> F["Model 10HBC-4"]
    E --> G["-SENSE"]
    F --> H["-EXC"]
    G --> I["SHIELD"]
    H --> J["Twisted Pair"]
    style A fill:#f9f,stroke:#333
    style B fill:#ccf,stroke:#333
    style C fill:#ccf,stroke:#333
    style D fill:#cfc,stroke:#333
    style E fill:#cfc,stroke:#333
    style F fill:#fcc,stroke:#333
    style G fill:#fcc,stroke:#333
    style H fill:#fcc,stroke:#333
    style I fill:#cff,stroke:#333

Fig. 2(d) Per-Channel Connections to Model 10HBC-4 for 6-Wire 1/2-Bridge Completion

graph TD
    A["+Excitation"] --> B["Swisted Pair"]
    C["Signal"] --> D["Swisted Pair"]
    E["-Excitation"] --> F["Swisted Pair"]
    B --> G["Model 10HBC-4"]
    D --> G
    F --> G
    G --> H["+EXC"]
    G --> I["+SENSE"]
    G --> J["CAL SEN"]
    G --> K["+SIGNAL"]
    G --> L["-SENSE"]
    G --> M["-EXC"]
    G --> N["SHIELD"]

Fig. 2(e) Per-Channel Connections to Model 10FBC-4 for Full-Bridge Connection

graph TD
    A["Resistors"] --> B["+Excitation"]
    B --> C["+Signal"]
    C --> D["-Excitation"]
    D --> E["-Signal"]
    F["Twisted Pair"] --> G["Model 10FBC-4"]
    G --> H["EXC"]
    G --> I["CAL SEN"]
    G --> J["+SIGNAL"]
    G --> K["-SENSE"]
    G --> L["-EXC"]
    G --> M["SHIELD"]
    style G fill:#f9f,stroke:#333
    style H fill:#ccf,stroke:#333
    style I fill:#ccf,stroke:#333
    style J fill:#ccf,stroke:#333
    style K fill:#ccf,stroke:#333
    style L fill:#ccf,stroke:#333
    style M fill:#ccf,stroke:#333

2.b 1/4-, 1/2-, OR FULL-BRIDGE GAGE CONNECTIONS USING THE MODEL 10CJB-4

Remove the top plate of the Model 10CJB-4 box (4 screws in corners). Inside the box are four sets of labelled screw terminals, one for each of the 10A73-4's input channels ("A," "B," "C," and "D"). You will connect your gage wires directly to these terminals, as shown in Fig. 3, and, if necessary, interconnect certain terminal pairs by means of jumper wires. Gage leads should enter the 10CJB-4 through the cutout on the right-hand side of the box.

NOTE: You must furnish your own pin-to-pin shielded cable for connecting the 10CJB-4 to the 10A73-4's rear I/O CONNECTOR (see Table 2 for pin assignments)—or you may use a special cable furnished by Daytronic. In either case, Daytronic will supply terminal connectors for the cable.

Fig. 3(a) shows connections between the 10CJB-4 and a 2-wire 1/4-bridge gage configuration (represented by the single gage resistor). Here, you must install a jumper wire between the -SIG and 1/2 BR terminals, and between the +SIG terminal and either the 120 terminal or the 350 terminal, depending on the nominal gage resistance.

Fig. 3 Model 10CJB-4 Transducer Cabling

graph TD
    A["Signal"] --> B["Excitation"]
    B --> C["-SIG"]
    B --> D["1/2 BR"]
    B --> E["-EX"]
    B --> F["120"]
    B --> G["350"]
    B --> H["+SIG"]
    B --> I["+EX"]
    J["Model 10CJ B-4 Screw Terminal (Chn. 1, 2, 3, or 4)"]

graph TD
    A["Signal"] --> B["Excitation"]
    B --> C["-SIG"]
    B --> D["1/2 BR"]
    B --> E["-EX"]
    B --> F["120"]
    B --> G["350"]
    B --> H["+SIG"]
    B --> I["+EX"]
    style A fill:#f9f,stroke:#333
    style B fill:#ccf,stroke:#333
    style C fill:#fff,stroke:#333
    style D fill:#fff,stroke:#333
    style E fill:#fff,stroke:#333
    style F fill:#fff,stroke:#333
    style G fill:#fff,stroke:#333
    style H fill:#fff,stroke:#333
    style I fill:#fff,stroke:#333

graph TD
    A["Signal"] --> B["-Excitation"]
    C["+ Excitation"] --> D["-SIG"]
    E["1/2 BR"] --> F["-EX"]
    G["120"] --> H["350"]
    I["+SIG"] --> J["+EX"]

Fig. 3(d) Full-Bridge Connection Model 10CJ B-4 Screw Terminal (Chn. 1, 2, 3, or 4) -Signal -Excitation +Signal + Excitation -SIG 1/2 BR -EX 120 350 +SIG +EX

graph TD
    subgraph_Channel_1["Channel 1"]
        direction TB
        A1["+ SIGNAL (CHN. 1)"]
        A2["CAL. SENSE (CHN. 1)"]
        A3["-SIGNAL (CHN. 1)"]
    end
    subgraph_Channel_2["Channel 2"]
        direction TB
        A4["+ SIGNAL (CHN. 2)"]
        A5["CAL. SENSE (CHN. 2)"]
        A6["-SIGNAL (CHN. 2)"]
    end
    subgraph_Channel_3["Channel 3"]
        direction TB
        A7["+ SIGNAL (CHN. 3)"]
        A8["CAL. SENSE (CHN. 3)"]
        A9["-Excitation"]
        direction TB
        A10["-SIGNAL (CHN. 3)"]
    end
    subgraph_Channel_4["Channel 4"]
        direction TB
        A11["+ SIGNAL (CHN. 4)"]
        A12["CAL. SENSE (CHN. 4)"]
        A13["-SIGNAL (CHN. 4)"]
    end
    D --> D1["D"]
    D --> D2["D"]
    D --> D3["D"]
    D --> D4["D"]
    D --> D5["D"]
    D --> D6["D"]
    D --> D7["D"]
    D --> D8["D"]
    D --> D9["D"]
    D --> D10["D"]
    D --> D11["D"]
    D --> D12["D"]
    D --> D13["D"]
    D --> D14["D"]
    D --> D15["D"]
    D --> D16["D"]
    D --> D17["D"]
    D --> D18["D"]
    D --> D19["D"]
    D --> D20["D"]
    D --> D21["D"]
    D --> D22["D"]
    D --> D23["D"]
    D --> D24["D"]
    D --> D25["D"]
    D --> D26["D"]
    D --> D27["D"]
    D --> D28["D"]
    D --> D29["D"]
    D --> D30["D"]
    D --> D31["D"]
    D --> D32["D"]
    D --> D33["D"]
    D --> D34["D"]
    D --> D35["D"]
    D --> D36["D"]
    D --> D37["D"]
    D --> D38["D"]
    D --> D39["D"]
    D --> D40["D"]
    D --> D41["D"]
    D --> D42["D"]
    D --> D43["D"]
    D --> D44["D"]
    D --> D45["D"]
    D --> D46["D"]
    D --> D47["D"]
    D --> D48["D"]
    D --> D49["D"]
    D --> D50["D"]
    D --> D51["D"]
    D --> D52["D"]
    D --> D53["D"]
    D --> D54["D"]
    D --> D55["D"]
    D --> D56["D"]
    D --> D57["D"]
    D --> D58["D"]
    D --> D59["D"]
    D --> D60["D"]
    D --> D61["D"]
    D --> D62["D"]
    D --> D63["D"]
    D --> D64["D"]
    D --> D65["D"]
    D --> D66["D"]
    D --> D67["D"]
    D --> D68["D"]
    D --> D69["D"]
    D --> D70["D"]
    style Channel_1 fill:#f9f,stroke:#333
    style Channel_2 fill:#f9f,stroke:#333
    style Channel_3 fill:#f9f,stroke:#333
    style Channel_4 fill:#f9f,stroke:#333
    style Channel_5 fill:#f9f,stroke:#333
    style Channel_6 fill:#f9f,stroke:#333
    style Channel_7 fill:#f9f,stroke:#333
    style Channel_8 fill:#f9f,stroke:#333
    style Channel_9 fill:#f9f,stroke:#333
    style Channel_10 fill:#f9f,stroke:#333
    style Channel_11 fill:#f9f,stroke:#333
    style Channel_12 fill:#f9f,stroke:#333
    style Channel_13 fill:#f9f,stroke:#333
    style Channel_14 fill:#f9f,stroke:#333
    style Channel_15 fill:#f9f,stroke:#333
    style Channel_16 fill:#f9f,stroke:#333
    style Channel_17 fill:#f9f,stroke:#333
    style Channel_18 fill:#f9f,stroke:#333
    style Channel_19 fill:#f9f,stroke:#333
    style Channel_20 fill:#f9f,stroke:#333
    style Channel_21 fill:#f9f,stroke:#333
    style Channel_22 fill:#f9f,stroke:#333
    style Channel_23 fill:#f9f,stroke:#333
    style Channel_24 fill:#f9f,stroke:#333
    style Channel_25 fill:#f9f,stroke:#333
    style Channel_26 fill:#f9f,stroke:#333
    style Channel_27 fill:#f9f,stroke:#333
    style Channel_28 fill:#f9f,stroke:#333
    style Channel_29 fill:#f9f,stroke:#333
    style Channel_30 fill:#f9f,stroke:#333
    style Channel_31 fill:#f9f,stroke:#333
    style Channel_32 fill:#f9f,stroke:#333
    style Channel_33 fill:#f9f,stroke:#333
    style Channel_34 fill:#f9f,stroke:#333
    style Channel_35 fill:#f9f,stroke:#333
    style Channel_36 fill:#f9f,stroke:#333
    style Channel_37 fill:#f9f,stroke:#333
    style Channel_38 fill:#f9f,stroke:#333
    style Channel_39 fill:#f9f,stroke:#333
    style Channel_40 fill:#f9f,stroke:#333
    style Channel_41 fill:#f9f,stroke:#333
    style Channel_42 fill:#f9f,stroke:#333
    style Channel_43 fill:#f9f,stroke:#333
    style Channel_44 fill:#f9f,stroke:#333
    style Channel_45 fill:#f9f,stroke:#333
    style Channel_46 fill:#f9f,stroke:#333
    style Channel_47 fill:#f9f,stroke:#333
    style Channel_48 fill:#f9f,stroke:#333
    style Channel_49 fill:#f9f,stroke:#333
    style Channel_50 fill:#f9f,stroke:#333
    style Channel_51 fill:#f9f,stroke:#333
    style Channel_52 fill:#f9f,stroke:#333
    style Channel_53 fill:#f9f,stroke:#333
    style Channel_54 fill:#f9f,stroke:#333
    style Channel_55 fill:#f9f,stroke:#333
    style Channel_56 fill:#f9f,stroke:#333
    style Channel_57 fill:#f9f,stroke:#333
    style Channel_58 fill:#f9f,stroke:#333
    style Channel_59 fill:#f9f,stroke:#333
    style Channel_60 fill:#f9f,stroke:#333

Fig. 4 10A73-4 Cabling to Four Full-Bridge Transducers

Fig. 3(b) shows connections between the 10CJB-4 and a 3-wire 1/4-bridge gage configuration (again represented by the single gage resistor). Here again, the -SIG and 1/2 BR terminals must be tied. The gage's third (self-compensating) lead is connected either to the 120 terminal or to the 350 terminal, depending on the nominal gage resistance.

Fig. 3(c) shows connections between the 10CJB-4 and a 1/2-bridge gage configuration (represented by the two connected gage resistors). Here again, the -SIG and 1/2 BR terminals must be tied.

Fig. 3(d) shows connections between the 10CJB-4 and a full-bridge gage configuration (represented by the four connected gage resistors).

2.c FULL-BRIDGE TRANSDUCER CONNECTIONS (WITHOUT BRIDGE COMPLETION)

In the absence of bridge-completion circuitry, the 10A73-4's I/O CONNECTOR will mate with Daytronic CONDITIONER CONNECTOR No. 60322, shown in Fig. 1.5 (in Manual Section 1.E.1). Pinout for the I/O CONNECTOR is given in Table 2, above. The required cabling is shown in Fig. 4, above.

Note that the main 16-wire shielded cable should contain 20- to 24-gage wires. The length of the main cable—i.e., the distance from the 10A73-4's rear I/O CONNECTOR to the two "sensing points"—may be up to 500 feet. At the sensing points, the + SENSE

and -SENSE lines join the corresponding EXCITATION lines, and the main cable divides into four separately shielded 5-wire cables (one to each full-bridge transducer). These secondary cables should contain 16- to 20-gage wires. It is important that the distance "D" from the sensing points to each transducer be as short as possible; a maximum error of 0.02% could arise for every 3.5 ft. of 20-gage wire over the distance "D," and for every 9 ft. of 16-gage wire.

3 SETUP AND/OR OPERATING CONSIDERATIONS

When a System 10 Bridge Completion Connector (Model 10QBC-4-120, 10QBC-4-350, 10QBC-4-1K, 10HBC-4, or 10FBC-4) is used with the Model 10A73-4, the excitation level for all four channels is fixed at 5 volts, and cannot be changed without a special modification to the 10A73-4 card.

When the Model 10CJB-4 Quad Bridge Completion Card is used with the Model 10A73-4, you will use the three-position switch on the 10CJB-4 board to set the excitation level for all four 10A73-4 channels to 1, 2, or 5 volts. The switch is shown in Fig. 5, below.

When a Bridge Completion Card or 10CJB-4 is absent, you may use Pin K of the 10A73-4's rear I/O CONNECTOR to select the desired excitation for all four channels, as indicated in Fig. 6. Leaving Pin K open selects an excitation of 5 volts; tying Pin K to Pin L selects 2 volts; and tying Pin K to Pin J selects 1 volt.

Fig. 5 Model 10CJB-4 Offset Jumpers and Excitation Selection Switch CONDITIONER CONNECTOR (No. 60322) Tie K to J for 1-V excitation Leave OPEN for 5-V excitation Tie K to L for 2-V excitation Fig. 6 Model 10A73-4 Excitation Selec- tion Without Bridge Completion

3.b CONFIGURATION AND CALIBRATION

For initial configuration of ANALOG INPUT CHANNELS dedicated to a specific Model 10A73-4 card when used in System 10, see the general remarks on System 10 "real-channel" configuration in Manual Section 1.G.1 and elsewhere in the System 10 Guidebook. For 10A73-4 channel "type" codes, see Table 1, above.

In System 10, when a Model 10A73-4 is connected to quarter-bridge or half-bridge gage configurations for purposes of stress analysis, you can perform both "CALCULATED" and "SIMULATED (SHUNT)" calibration of any of its input channels, regardless of the type of bridge completion being used for that channel. In general, the conventional "TWO-POINT (DEADWEIGHT)" method does not apply in such cases.

When a 10A73-4 is connected to full-bridge strain gage transducers, "TWO-POINT (DEADWEIGHT)" calibration may be applied, in addition to or as an alternative to "CAL-CULATED" and "SIMULATED (SHUNT)" calibration.

NOTE: If you are using a Model 10CJB-4 for bridge completion of a 10A73-4 channel and, prior to initial calibration, observe a significantly nonzero reading when no load is placed on the gage(s), you may impose a nominal ±1 mV/V offset by means of solder pads in the 10CJB-4 box. See Section 3.c for complete instructions.

CALCULATED CALIBRATION

To calibrate a 10A73-4-based Channel No. "x,"

1. Turn ON the system EEPROM SWITCH and then apply the following MV/V CALIBRATION (MVV) command:

$$ \mathbf {M V V} \mathbf {x} = \mathbf {i}, \mathbf {u} [ \mathbf {C R} ] $$

For “i” (the transducer sensitivity rating), you should enter one of the following full-scale “mV/V” values, whichever corresponds to the channel’s “type” setting (see Table 1): 0.750 (for “Type 70”), 1.500 (for “Type 71”), or 3.000 (for “Type 72”).

For “u” (the nominal full-scale rating), you should enter the full-scale microstrain range that corresponds to the selected transducer sensitivity rating, as given in the following table:

Table 3 Strain Gage Microstrain Ranges (10A73-4)

Full-Scale Full-ScaleOutput (mV/V) Microstrain Range

0.750 u = 3000 / (N · G)

1.500 u = 6000 / (N · G)

3.000 u = 12000 / (N · G)

Here, “N” is the number of active strain-gage arms in the gage configuration. Thus, for a 1/4-bridge gage, N = 1; for a half-bridge gage, N = 2; and for a full-bridge gage, N = 4. “G” is the gage factor of the strain gage, and is normally provided by the manufacturer.

The MVV command will only work if Channel No. x has been assigned the proper "type" code ("70," "71," or "72"). Note that a channel calibrated by the MVV command will report measurement data to a precision matching that of the entered "u" value.

1. Zero the channel by commanding

ZRO x [CR]

Two-Point (Deadweight) Calibration

PLEASE NOTE: AS MENTIONED ABOVE, THIS CALIBRATION TECHNIQUE GENERALLY APPLIES TO A MODEL 10A73-4 CHANNEL ONLY WHEN THAT CHANNEL IS CONNECTED TO A FULL-BRIDGE STRAIN GAGE TRANSDUCER, AS ARE THE FOUR CHANNELS SHOWN IN FIG. 4.

Using the standard ZERO (ZRO) and FORCE (FRC) commands, this conventional "zero and span" method can be applied to a "full-bridge" 10A73-4 channel if the full-scale "mV/V" rating of the channel's strain gage transducer is unknown, or if the final measurement accuracy provided by CALCULATED CALIBRATION does not meet the requirements of the measurement application. The mainframe's EEPROM Write Protect Switch must be ON for the ZRO and FRC commands to be effective. See Manual Section 1.G.5 for a general discussion of this calibration technique.

SIMULATED (SHUNT) CALIBRATION

This is a convenient “shunt resistor” method, where the second (“span”) input is not produced by loading the source transducer, but by “simulating” a particular up-scale value of mechanical input. This known EQUIVALENT INPUT then serves to determine the SCALING FACTOR for the channel.*

For a 10A73-4 data channel, the equivalent input is produced by shunting a resistor of known magnitude across one arm of the strain gage bridge, thereby simulating a known value of input for either a positive or negative up-scale reading. If the transducer manufacturer has supplied the exact value of the transducer's equivalent input, it can be used as a reference point for calibrating the channel.

Equivalent input can be approximated from a knowledge of the Shunt Calibration Resistance (R), the transducer's Bridge Resistance (B), and the transducer's Full-Scale Sensitivity (K, in mV/V full scale). To determine the EQUIVALENT INPUT (X) as an approximate percentage of full-scale output, you may use the following equation:

$$ \mathbf {X} = 25000 \mathbf {B} / \mathbf {K} (\mathbf {R} + 0.5 \mathbf {B}) $$

Since the equivalent input is here expressed as a percentage of full-scale output, you must multiply it by the rated full-scale capacity of the transducer, in order to determine the actual input simulated by the shunt.

IMPORTANT: FOR A 10A73-4 CHANNEL WITH BRIDGE COMPLETION—BY MEANS EITHER OF A SYSTEM BRIDGE COMPLETION CONNECTOR OR THE MODEL 10CJB-4—THE EQUIVALENT INPUT SHOULD BE EXPRESSED IN MICROSTRAIN (MICROINCHES/INCH).

Fig. 7 Model 10A73-4 Shunt Calibration Resistors

Terminal post for connection of shunt resistor Rear I/O Connector Side 2

* Shunt calibration is easier though generally less accurate than two-point (deadweight) calibration. It is good for an accuracy of about 0.2% (depending, of course, on the accuracy of the specified equivalent input, and on the resistor/bridge tolerance and temperature).

Fig. 8 Logic Inputs for 10A73-4 Remote Shunt Calibration (Without Bridge Completion)

CONDITIONER CONNECTOR (No. 60322) A 1 B 2 C 3 D 4 E 5 F 6 H 7 J 8 K 9 L 10 + CALIBRATE PWR COMMON - CALIBRATE A OPEN = Logic 1 (NO ±Calibration) CLOSED = Logic 0 (±Calibration) B CONDITIONER CONNECTOR (No. 60322) A 1 B 2 C 3 D 4 E 5 F 6 H 7 J 8 K 9 L 10 + CALIBRATE PWR COMMON - CALIBRATE Fig. 8(a) Switch Closure, No External Supply Fig. 8(b) Active TTL Logic

The 10A73-4 is equipped with a 100-kΩ, 0.1% calibration resistor for each active channel. These resistors are located on turret terminals at the rear of the card (see Fig. 7). You may, if you wish, replace each channel's installed 100K shunt resistor with a resistor of another value (strain-gage transducer manufacturers often supply such resistors with their instruments).

In System 10, a strain gage channel's shunt resistor may be switched in and out by means of the SHUNT CALIBRATE-POSITIVE (SHP) or SHUNT CALIBRATE-NEGATIVE (SHN) command. A RESUME (RSM) command should then be applied to remove the shunt and resume normal channel measurement. Since these are "runtime" commands, the mainframe's EEPROM Write Protect Switch need not be on for them to be effective. See Manual Section 1.G.6 for general instructions regarding the "SHUNT CALIBRATION" technique in System 10.

NOTE: All four channels' calibration shunts can be simultaneously and "remotely" controlled, if desired, as an alternative to using the software "SHUNT CALIBRATE" commands provided by the system, provided that a System 10 BRIDGE COMPLETION CONNECTOR is not attached to the card.* This remote calibration control is accomplished by means of logic-level inputs to the 10A73-4 card. The relevant connections are given in Fig. 8.

Fig. 8(a) shows how the "CALIBRATE POSITIVE" and "CALIBRATE NEGATIVE" commands can be independently applied to all four 10A73-4 channels simultaneously, without the need of an external logic reference supply.

Closing the switch in Fig. 8(a) to contact point "A" will produce a Logic 0 level at Pin 9 ("NOT + CALIBRATE"). Since this is a negative-true logic line, the Logic 0 input will activate the "+CALIBRATE" condition for all four channels. That is, it will switch in each channel's shunt resistor for a positive up-scale reading. Opening the switch to disconnect the "NOT + CALIBRATE" line from POWER COMMON will then return all channels to the "NO + CALIBRATE" condition.

Similarly, closing the switch to contact point "B" will produce a Logic 0 level at Pin 10 ("NOT -CALIBRATE"), thereby switching in each channel's shunt resistor for a negative up-scale reading. Opening the switch to disconnect the "NOT -CALIBRATE" line from POWER COMMON will then return all channels to the "NO -CALIBRATE" condition.

You may also use active TTL logic, as illustrated in Fig. 8(b), to produce the “+CALIBRATE” or “-CALIBRATE” condition for all four 10A73-4 channels.

3.c SETTING AN INITIAL ZERO OFFSET WITH THE MODEL 10CJB-4

Often the very process of mounting strain gages to the stressed material can introduce a significant residual strain, which will become apparent as a large nonzero offset in the data reading prior to initial calibration. When you are using the Model 10CJB-4 Quad Bridge Completion Card with the Model 10A73-4, you can remove at least a portion of this initial strain component for a given 10A73-4 channel by applying an approximate 1 mV/V positive or negative offset, as follows:

1. Remove the top plate of the 10CJB-4 box (4 screws in corners).
2. Refer to Fig. 5 and locate the set of three "1 MV/V OFFSET" jumper pads corresponding to the channel in question (like the 10CJB-4's terminal blocks, the pad sets are labelled "A," "B," "C," and "D"—corresponding to 10A73-4 Subchannel Nos 1, 2, 3, and 4, respectively).
3. Remove all load from the source gage(s).
4. Observe the data reading of the channel. If it is a positive nonzero value, apply a negative 1 mV/V offset by carefully placing a solder drop between the center pad and the “−” pad. If it is a negative nonzero value, place a solder drop between the center pad and the “+” pad.
5. Now calibrate the channel to remove any remaining offset.

4 LEAD-WIRE AND NONLINEARITY EFFECTS WITH QUARTER-BRIDGE STRAIN GAGE CONFIGURATION

In stress analysis applications, it often happens that the completion resistors for a quarter-bridge strain gage are located some distance from the gage. If the resistance of the wires connecting the gage to the completion circuitry is considerable, it can "desensitize" the bridge, producing less output voltage from the bridge for a given amount of strain as the wire resistance increases.

A second cause of possible inaccuracy is the slight nonlinearity inherent in all bridge configurations. This nonlinearity is proportional to the amount of "upset" of the bridge. For small amounts of strain (below about 5000 microstrain, with a gage factor of 2), the output is nearly linear. However, as the change in gage resistance increases due to increasing strain, the nonlinearity effect becomes measurable.

4.a PREVENTING THE EFFECTS OF LEAD-WIRE RESISTANCE

When connecting a Model 10A73-4 to a quarter-bridge strain gage configuration, you can eliminate all effects of reasonable lead wire resistance by using a Model 10CJB-4

graph TD
    A["+S"] --> B["Gage & Cable"]
    B --> C["Rb"]
    C --> D["Rb"]
    D --> E["+Exc"]
    E --> F["+Sense"]
    F --> G["To +Exc Circuit"]
    H["Rb"] --> I["Gage & Cable"]
    I --> J["Rb"]
    J --> K["-S"]
    K --> L["+Signal"]
    L --> M["Cal Sense"]
    M --> N["Rs (100K .1% provided)"]
    N --> O["A"]
    O --> P["Negative"]
    P --> Q["Positive Resume"]
    Q --> R["To First Amp"]
    S["-S"] --> T["Rb"]
    T --> U["Cable to Bridge Compl. Circuit"]
    V["-S"] --> W["-Exc"]
    W --> X["Cable to Bridge Compl. Circuit"]
    Y["S"] --> Z["-Signal"]
    Z --> AA["Cal Sense"]
    AB["S"] --> AC["-Sense"]
    AC --> AD["Cable to Bridge Compl. Circuit"]
    AE["S"] --> AF["-Exc"]
    AF --> AG["Cable to Bridge Compl. Circuit"]
    AH["S"] --> AI["Cable to Bridge Compl. Circuit"]
    AJ["S"] --> AK["Cable to Bridge Compl. Circuit"]
    AL["S"] --> AM["Cable to Bridge Compl. Circuit"]
    AN["S"] --> AO["Cable to Bridge Compl. Circuit"]
    AP["S"] --> AQ["Cable to Bridge Compl. Circuit"]
    AR["S"] --> AS["Cable to Bridge Compl. Circuit"]
    AT["S"] --> AU["Cable to Bridge Compl. Circuit"]
    AV["S"] --> AW["Cable to Bridge Compl. Circuit"]
    AX["S"] --> AY["Cable to Bridge Compl. Circuit"]
    AZ["S"] --> BA["Cable to Bridge Compl. Circuit"]
    BB["S"] --> BC["Cable to Bridge Compl. Circuit"]
    BD["S"] --> BE["Cable to Bridge Compl. Circuit"]
    BF["S"] --> BG["Cable to Bridge Compl. Circuit"]
    BH["S"] --> BI["Cable to Bridge Compl. Circuit"]
    BJ["S"] --> BK["Cable to Bridge Compl. Circuit"]
    BL["S"] --> BM["Cable to Bridge Compl. Circuit"]
    BN["S"] --> BO["Cable to Bridge Compl. Circuit"]
    BP["S"] --> BQ["Cable to Bridge Compl. Circuit"]
    BR["S"] --> BS["Cable to Bridge Compl. Circuit"]
    BT["S"] --> BU["Cable to Bridge Compl. Circuit"]
    BV["S"] --> BW["Cable to Bridge Compl. Circuit"]
    BX["S"] --> BY["Cable to Bridge Compl. Circuit"]
    BZ["S"] --> CA["Bridge Completion Circuit"]
    CA --> CB["+Exc"]
    CA --> CC["+Sense"]
    CA --> DD["Cal Sense"]
    CA --> DE["-Signal"]
    CA --> EF["-Exc"]
    CA --> GF["Cable to Bridge Compl. Circuit"]
    DG["S"] --> DH["Shunt Circuit on Conditioner Card (simplified)"]
    DI["S"] --> DJ["Shunt Circuit on Conditioner Card (simplified)"]
    DK["S"] --> DL["Shunt Circuit on Conditioner Card (simplified)"]
    DV["S"] --> DW["Shunt Circuit on Conditioner Card (simplified)"]
    DX["S"] --> DXA["Shunt Circuit on Conditioner Card (simplified)"]
    DXB["S"] --> DXC["Shunt Circuit on Conditioner Card (simplified)"]

Fig. 9 Shunt Calibration with a 3-Wire, Single-Active Strain Gage

Four-Channel Bridge Completion Card in the vicinity of the gages, since the 10CJB-4 has inherent bridge-voltage sensing. WHERE THIS IS NOT POSSIBLE, YOU SHOULD USE A SHUNT CALIBRATION PROCEDURE with a three-wire run to the gage (see Fig. 9).*

Use the shunt ONLY ON THE INACTIVE COMPLETION ARM, AS SHOWN, INSTEAD OF ON THE GAGE ARM. To find the EQUIVALENT STRAIN (S) for a given GAGE FACTOR (G), BRIDGE RESISTANCE ( R_b ), and SHUNT RESISTANCE ( R_s ), use this expression:

$$ \mathbf {S} = \mathbf {R} _ {\mathrm{b}} / \mathbf {G} (\mathbf {R} _ {\mathrm{b}} + \mathbf {R} _ {\mathrm{s}}) $$

To determine the shunt resistance required to simulate a given amount of strain, you can solve for R_s :

$$ \mathbf {R} _ {\mathrm{s}} = \mathbf {R} _ {\mathrm{b}} (1 - \mathbf {G S}) / \mathbf {G S} $$

If shunt calibration is not possible, you can alternatively compensate for the effects of lead wire resistance by applying a CORRECTED SCALING FACTOR of

$$ \mathbf {m} _ {\mathrm{c}} = \mathbf {m} (1 + R _ {\mathrm{L}} / R _ {\mathrm{b}}) $$

where "m" is the "normal" SCALING FACTOR ("m" coefficient), which is determined for the strain gage conditioner during calibration (see Section 3.b, above); "R L " is the lead wire resistance; and "R b " is the resistance of each of the three bridge-completion resistors (see Fig. 9).

Suppose, for example, that you are using a Model 10A73-4 channel for quarter-bridge strain measurement, with bridge completion provided by the Model 10QBC-4. Assume a gage factor ("G") of 2, a lead wire resistance R_L of 2.5 Ω, and a bridge resistance R_b of 350 Ω. If the 10A73-4 channel is configured for full-scale ±30,000 μS (= 0.03 S), its normal "m" factor is determined by the equation

$$ \mathrm{m} = 6 0, 0 0 0 / (\mathrm{N} \times \mathrm{G}) $$

as explained in Section 3.b. Since the number of gages (N) = 1,

$$ \mathrm{m} = 6 0, 0 0 0 / \mathrm{G} = 3 0, 0 0 0 $$

* Buffered by a low-offset, low-drift, high-impedance, unity-gain amplifier (A), the solid-state shunt-calibration switch prevents the shunt current from flowing in the excitation sense lines. The switch itself is controlled by the software SHUNT CALIBRATE-POSITIVE (SHP), SHUNT CALIBRATE-NEGATIVE (SHN), and RESUME (RSM) commands.

—and the corrected SCALING FACTOR in units of STRAIN is therefore

$$ \mathrm{m} _ {\mathrm{c}} = (3 0, 0 0 0) \left(1 + \mathrm{R} _ {\mathrm{L}} / \mathrm{R} _ {\mathrm{b}}\right) = (3 0, 0 0 0) (1. 0 0 7) = 3 0, 2 1 0 $$

This corrected factor can then be applied to the strain gage channel in question by means of the SCALING FACTOR (EMM) command.

4.b PREVENTING THE EFFECTS OF BRIDGE NONLINEARITY

The effects of this nonlinearity can be minimized by SHUNT CALIBRATION at 80% of the expected full-scale strain, thus distributing it more uniformly over the range. WHERE THE GAGE IS TO BE USED IN EITHER TENSION OR COMPRESSION MEASUREMENTS—BUT NOT BOTH—an additional compensating term can be employed to determine the fully corrected SCALING FACTOR:

$$ \mathbf {m} _ {\mathrm{c}} = \mathbf {m} (1 + \mathbf {R} _ {\mathrm{L}} / \mathbf {R} _ {\mathrm{b}} \pm (\mathbf {G S}) / 2) $$

Choose the STRAIN (S) to equal 80% of the expected maximum strain. IF THE GAGE IS USED IN TENSION MEASUREMENT, THE TERM "(GS)/2" IS TO BE ADDED; IF IT IS USED IN COMPRESSION MEASUREMENT, THE TERM IS TO BE SUBTRACTED. Note too that the lead wire correction term " R_L/R_b " can be discarded if its contribution is negligible.

Using the same example as above, where "S" = 0.03, and now assuming that the gage is intended to measure TENSION only, we have

$$ \mathrm{m} _ {\mathrm{c}} = (3 0, 0 0 0) \left(1 + \mathrm{R} _ {\mathrm{L}} / \mathrm{R} _ {\mathrm{b}} + (\mathrm{GS}) / 2\right) = (3 0, 0 0 0) (1. 0 3 7) = 3 1, 1 1 0 $$