OMEGA LDX-D (01) PDF DOCUMENT

Please observe the following guidelines during the installation or adjustment of your OMEGA LDX-D to prevent personal injury or damage to the equipment.

WARNINGS & CAUTIONS:

WARNING: Do not operate the OMEGA LDX-D in an explosive atmosphere.

WARNING: This equipment is not intended for use in a safety-critical environment.

CAUTION: The OMEGA LDX-D is designed to work from a low voltage DC supply. Do not operate this equipment outside of the specified voltage range.

CAUTION: Electrostatic Discharge (ESD)

The OMEGA LDX-D is susceptible to electrostatic discharge. To prevent ESD-related damage, handle the unit by its case and do not touch the connector pins, especially when the case cover is removed.

Installation Guidelines:

• Ensure all power supplies are turned off before starting.

• If possible, wear an ESD strap connected to the ground. If not possible, discharge yourself by touching a metal part of the equipment into which the conditioning electronics is being installed.

• Connect the transducer and power supplies with the power switched off.

• Ensure any tools are discharged by contacting them against a metal part of the equipment before use.

• When setting up the conditioning electronics, make link configuration changes with the power supply turned off. Avoid touching any other components.

• Make the final gain and offset potentiometer adjustments with the power applied, using an appropriate potentiometer adjustment tool or a small insulated screwdriver.

Before mounting, please review the placement and EMC guidelines.

Mounting on a DIN Rail:

1. Hook the OMEGA LDX-D onto the DIN rail with the release clip facing down.

2. Push the unit onto the rail until a ‘click’ is heard.

Removing from a DIN Rail:

1. Use a screwdriver to lever the release clip down.

2. Pull the bottom of the housing away from the rail and unhook it.

Accessing Internal Links and PCB:

1. To access the internal links, the front cover and PCB must be withdrawn from the housing.

2. Use a screwdriver or similar tool to depress the top cover release latch. The cover will spring forward.

3. Repeat for the bottom latch.

4. Gently pull the PCB out of the housing.

The OMEGA LDX-D has the following terminal connections:

Transducer Connections:

• Terminal 1: Synchronization 1 (Sy1)

• Terminal 2: Synchronization 2 (Sy2)

• Terminal 3: Primary (red) (pri1)

• Terminal 4: Primary (blue) (pri2)

• Terminal 5: Screen (0 V) (scn)

• Terminal 6: CT (yellow)

• Terminal 7: Secondary (green) (sec1)

• Terminal 8: Secondary (white) (sec2)

Power Supply & Output Connections:

• Terminal 9: Voltage Output (Vout)

• Terminal 10: Math OUT (Mout)

• Terminal 11: Signal 0 V (OV)

• Terminal 12: Current OUT (Iout)

• Terminal 13: Math External IN (Min)

• Terminal 14: Inverted Math OUT (Mout#)

• Terminal 15: -VE power supply

• Terminal 16: +VE power supply

Note: Terminals 5, 11, and 15 are internally connected, but for best performance, they should be treated as separate terminals. If the output polarity is incorrect, reverse the transducer secondary connections (terminals 7 and 8).

The following tables describe the electrical connections for Omega LVDT and Half Bridge transducers.

LVDT Electrical Connections

Half Bridge Electrical Connections

The CT terminal (6) is provided to terminate the center tap (CT) connection of a transducer if present. There is no electrical connection within the OMEGA LDX-D for this terminal. It is provided to allow for quadrature components to be fitted if required.

The internal links on the OMEGA LDX-D are used to configure the module’s operation. The following table explains their functions and factory settings. A “PARKED” link is a link that is placed on only one pin, effectively storing it without making a connection.

Primary Frequency:

The primary frequency is set using links. The optimum frequency is determined by the transducer’s specifications. The options are 5 kHz, 10 kHz, and 13 kHz. Set the links on the “PRIMARY” header according to the markings on the PCB.

Transducer Input Load:

The OMEGA LDX-D has two input load ranges, set by the “INPUT LOAD” link.

• 100 kΩ: Set the link to the PARKED position. This is often used for LVDT transducers.

• 2 kΩ: Set the link to the ON position. This is often used for Half Bridge transducers.

If a load of less than 100 kΩ is required, an external resistor may be wired across the SEC1 (7) and SEC2 (8) terminals.

Bandwidth (BW):

The OMEGA LDX-D has a selectable output signal bandwidth. Where possible, use the lowest bandwidth setting to minimize output noise.

• 500 Hz: Set the “BW” link to the ON position (L).

• 1 kHz: Set the “BW” link to the PARKED position (H).

The following is a typical setup procedure. For bi-polar outputs (e.g., ±10 VDC), follow steps 1 to 3. For uni-polar outputs (e.g., 0-10 VDC), follow steps 1 to 4. In all cases, step 5 should be performed.

Step 1: Set up LDX-D Links

• If the transducer characteristics are known, set the frequency and input resistance links as required. If in doubt, use the factory settings. Ensure offset and MATH options are not set initially.

• If the transducer is outside the standard sensitivity range, the input gain links (X1, X2, X5, DIV2) will need to be used.

Step 2: Align LDX-D and Transducer Null

This step aligns the electrical null of the LDX-D with the mechanical null of the transducer.

1. Null the LDX-D: Put the COARSE GAIN link onto the “null” position (marked on the PCB). This temporarily shorts the transducer input. Adjust the fine “Offset” control to get the output as close to zero as practical.

2. Null the Transducer: Replace the COARSE GAIN link to its original position. Adjust the physical position of the transducer to its mechanical center (null) to give as near zero output as practical.

Step 3: Setting Bi-polar (±) Full Scale Output

1. Move the transducer to the position where maximum output is required.

2. If the output polarity is wrong, reverse the transducer secondary connections (terminals 7 & 8) and re-check the zero position.

3. Move the COARSE GAIN link along from position 1 towards position 6 until the output is near the required value.

4. Adjust the fine “Gain” control to give the precise required output.

5. The bi-polar output is now set. Proceed to Step 5.

Step 4: Setting Uni-polar Full Scale Output (Adding an Offset)

1. Move the transducer to the null position. The LDX-D output will be 0 V or 0 mA.

2. Apply a coarse offset using the +VE, -VE, 5V, or 10V COARSE OFFSET links. Adjust the fine “Offset” control to set the output precisely. For example, for a 0-10 V output, you would set a bi-polar range of ±5V, then add a +5V offset at the null position.

Step 5: Final Checks

• Ensure calibration is correct by moving the transducer across its required mechanical range (including the mid position) and checking the calibration points. Fine adjustments can be made if required.

The OMEGA LDX-D provides several related outputs. All outputs are affected by changes made to the Vout gain and offset controls and cannot be independently adjusted.

• Vout (Voltage Output): This is the primary voltage output. The gain and offset controls are used to set the required output range (e.g., ±10 V).

• Iout (Current Output): This is a current output, proportional to Vout. It is not loop-powered. It can be set for up to ±20 mA. A common range is 4-20 mA, which corresponds to a 2 to 10 V span on Vout.

• Mout (MATH Output): This is the main voltage output of the MATH section. When two LDX-D units are linked for a math function, this terminal provides the result. If MATH options are not selected, Mout is proportional to Vout.

• Mout# (Inverted MATH Output): This is an auxiliary voltage output that is the direct output of the MATH stage and is the inverse of Vout. If MATH options are not selected, then Mout# is also proportional to Vout.

The approximate relationship between voltage and current output is shown below:

If the transducer output signal is too high or too low, it can degrade performance. You may need to change the input gain setting from the standard X1. First, calculate the transducer Full Range Output (FRO).

Calculating Transducer FRO:

Transducer sensitivity is typically quoted as mV/V/mm.

FRO = (Sensitivity in mV/V/mm) x (LDX-D primary voltage) x (Transducer range in mm from null)

The OMEGA LDX-D primary voltage is 3 V.

Example: A transducer has a sensitivity of 210 mV/V/mm and a range of ±1 mm.

FRO = 210 x 3 x 1 = 630 mV (0.63 V). This falls within the standard range.

Use the following table to set the “INPUT GAIN” link based on your calculated FRO:

By linking two OMEGA LDX-D modules, you can perform analog arithmetic such as A+B, A-B, (A+B)/2, and (A-B)/2.

Connection:

Connect the Vout (terminal 9) of the first module (LDX-D A) to the Min (terminal 13) of the second module (LDX-D B). The result of the calculation is then available at the Mout (terminal 10) of LDX-D B.

Setup Procedure:

1. Requirements: Determine the arithmetic function and the required output range. The Vout of each LDX-D is used for the calculation. Be aware of the output limits. For example, to get an A-B result of ±10 V, you cannot set each module to ±10 V, as the result could be ±20 V, which is not possible. Instead, you could set each module to ±5 V for A-B, or set each to ±10 V and use the (A-B)/2 math function.

2. Initial Set-up: Set up each OMEGA LDX-D module individually first, following the standard setup procedure to null the transducer and set the gain for the desired bi-polar voltage range (e.g., ±5 V).

3. Configure MATH Links: On LDX-D B (the module receiving the input on Min), set the “MATH” links to the desired function: A+B, A-B, (A+B)/2, or (A-B)/2. There is also a “Mout=Vout” setting.

4. Final Checks: After connecting the modules, an offset may be seen at the final Mout terminal due to inherent offsets in the MATH circuits. To remove this, adjust one of the Vout fine offset controls (preferably on LDX-D B) while both transducers are at their null positions until the Mout of LDX-D B is zero.

Synchronization of the primary oscillator phase is only required in installations where multiple transducers and their cables are in close proximity and electrical interaction or cross-talk is observed. This may be seen as a change in output from one module when the probe connected to an adjacent module is moved.

To synchronize modules:

1. Designate one OMEGA LDX-D module as the “MASTER”.

2. Designate all other modules as “TRACK”.

3. On the PCB of each module, set the “MT” (Master/Track) link accordingly. The “MASTER” setting is the factory default.

4. Connect the Sy1 (terminal 1) and Sy2 (terminal 2) terminals of all modules together (Sy1 to Sy1, Sy2 to Sy2).

The master module will now control the oscillator timing for all tracked modules.

For best performance and to comply with EMC regulations, consider the installation environment.

Residential, Commercial, and Light Industrial Environments:

In environments without high levels of electrical interference (e.g., offices, laboratories), connections can be made using twisted unscreened wire (e.g., 7/0.2 or 24AWG) or standard data cable like CAT5 UTP for good performance.

Industrial Environments:

In environments with equipment like welders or large motors that produce high levels of EMI, follow these guidelines:

• Mount the OMEGA LDX-D inside an industrial steel enclosure designed for EMI screening.

• Place the OMEGA LDX-D away from equipment within the enclosure that is likely to produce high levels of EMI.

• Connections should be made using a screened cable (braided or foil). Keep exposed, unscreened sections of cable as short as possible.

• The cable screen should be connected to the housing at the cable entry point, preferably using an EMC cable gland. If not possible, connect the screen to a local ground.

Grounding:

• Where possible, the OMEGA LDX-D should be the only ground connection point to avoid noise from ground loops.

• All 0 V terminals on the LDX-D are connected internally. The system ground may be connected to any 0 V terminal, but terminal 11 (Signal 0V) is preferred. The cable screen can also be connected via terminal 11.

• A local power supply is ideal. If not possible, using a screened cable for the power supply can help reduce noise.