The SCMVAS (Signal Conditioning Modular Voltage Attenuator System) is an analog signal conditioning system designed to safely monitor and accurately measure voltage potentials up to 495VAC (1400V peak-to-peak). These highlevel voltages are typically found in industrial applications such as induction heaters or electric-motor drive controllers. The system reduces the input signal to a level suitable for interface to data acquisition systems, while at the same time providing various filter characteristics and 1500Vrms isolation.
For each channel of analog input, an attenuator module, SCMVAS-Mnnn, pre-conditions the signal which is then filtered, isolated, and converted to a high-level voltage output using an SCM5B30-07 or SCM5B40-07 module. The SCM5B40-07 module with a 10kHz bandwidth is recommended for common 50/60Hz signals low in harmonics where the user is interested in measuring only AC voltage. The SCM5B30-07 module is used for low frequency AC signals below 4Hz. For signals comprised of harmonics or noncoherent content, the SCM5B33 True RMS Input module is recommended. Use of this module provides a DC output that is directly related to input signal power, or the RMS (Root Mean Square) value, allowing true RMS representation of input signals ranging from pulses to complex nonperiodic waveforms. The attenuator and signal conditioning modules have excellent stability over time and do not require recalibration. Overall system accuracy is ±0.06%.
Input signal connections to the SCMVAS-Mnnn attenuator module are made using a pluggable terminal block for ease of system assembly and reconfiguration. For safety purposes, the terminal block has a cover over the screws and there are no other exposed high-voltage points on the SCMVAS-Mnnn series modules, SCM5B30-07 or SCM5B40-07 module, or the mounting backpanel.
The SCMVAS system has two specially designed backpanels for mounting the attenuator and signal conditioning modules. The SCMVAS-PB8 high density, 8-channel backpanel can be panel mounted or DIN rail mounted and provides the conditioned output signal on screw terminal blocks. Jumpers are provided on each channel to optionally connect or isolate each module’s I/O Common from other channel’s I/O Common and/or Power Common. The SCMVAS-PB16 has 16 channels of analog I/O simultaneously available to high-speed data acquisition (ADC) boards through a 26-conductor ribbon cable. Refer to the SCMPB01 Data Sheet in the catalog and Application Note AN502 on the website for recommended ground connections and host system interfaces. Both the SCMVAS-PB8 and SCMVAS-PB16 backpanels can be mounted on the SCMXRK-002 19-inch metal rack.
Frequently Asked Questions
Can Dataforth provide calibration reports for modules I purchased?
Yes we can provide calibration reports for the modules that you purchased.
You can either
a) visit https://www.dataforth.com/TestDataReport.aspx to search for Test Report Datasheets by Serial Number or
b) you can send us a list of model numbers and their serial numbers to firstname.lastname@example.org
Is the calibration of Dataforth modules traceable to NIST standards?
Yes, calibration of Dataforth modules is traceable to NIST standards.
Analog Devices announced a last time buy and discontinuance of their signal conditioning modules. Can I replace them with Dataforth signal conditioning modules?
Yes, in general, Dataforth signal conditioning modules are a direct replacement for all Analog Devices signal conditioning modules. e.g. "SCM5B35-xx: Linearized 4-Wire RTD Input Modules" will replace Analog Devices "5B35: Isolated 4 Wire RTD Input Signal Conditioning Module".
Please note that Dataforth signal conditioning modules are RoHS II compliant.
What is the recommended power supply for Dataforth SCM5B and 8B modules?
The recommended power supply for the Dataforth SCM5B and 8B modules are the linear power supplies in our SCMXPRT/SCMXPRE series. The SCMXPRT/SCMXPRE power supplies output 5V and have options for 1A output current (SCMXPRT-001) or 3A output current (SCMXPRT-003).
The SCMXPRE series is identical to its SCMXPRT counterpart, but is configured for European voltage standards.
The SCMXPRT-001/SCMXPRE-001 both have the option for DIN rail mounting as well (SCMXPRT-001D/SCMXPRE-001D).
Other power supplies that meet that power requirements of the SCM5B and 8B modules can be used as well, but it is strongly recommended to use a linear power supply rather than a switch-mode power supply. Switching power supplies can add noise artifacts to the output of your modules.
Can I use an SCM5B41-07 in my SCMVAS system?
Technically, yes you could use an SCM5B41-07 in your SCMVAS system. However, it is not recommended since the output of all SCMVAS modules are -1 V to 1 V. Since the SCM5B41-07 has a -20 V to 20 V input range, most of that range will go unused while your accuracy suffers as a result since the SCM5B line has +/-0.03% span accuracy.
I just received an SCMPB01 back panel. How should I configure jumpers J1 through J4 for my application?
The factory configuration for jumpers J1 through J4 is the optimal configuration for most applications. If for some reason this jumper configuration will not work/is not working in your application, see our application note AN502 "Ground Connections and Host System Interfaces" for other valid jumper configurations and what situations you would use them.
Do you have any SCM5B modules with a 50kHz bandwidth?
None of our standard SCM5B modules have a 50kHz bandwidth. However, it is possible to order a custom SCM5B module with 50kHz bandwidth. Keep in mind that new customs require a 10 pc minimum order and are subject to extra design fees.
Do you have an MTBF figure for the SCM5B39? What are the main failure modes?
The failure rate calculations for our SCM5B modules can be found in our application note AN503: https://www.dataforth.com/catalog/pdf/an503.pdf
There are no dominant failure modes.
Can SCM5B modules be hot swapped?
Not just SCM5B modules, but any signal conditioning module series and MAQ20 I/O modules can be hot swapped. A minimal amount of signal settling time may result, but there will be no damage to the device.
Where can I find the pinout of my SCM5B module?
Please see the SCM5B Module Dimensions and Pinouts link from the SCM5B section of our website: https://www.dataforth.com/catalog/pdf/scm5bdim.pdf
You can also find the module dimensions and pinouts in our product catalog.
Where can I find the MTBF of my module?
Information on MTBF for SCM5B, SCM7B, 8B and DSCA is available on our website. Please see application note AN802 for more details. Application notes can be found under the "Literature" tab on the top navigation bar.
What is the required resistance for jumpers J1 through J4 on my SCM5B backpanel?
J1-J4 on the SCM5B backpanels are jumper cables, so they should have 0 ohm resistance.
What does "Response time, 90% span" mean on the datasheet for my module?
Normally, a response time figure refers to how quickly a module's output can "respond" to a change in the input signal. "Response time, 90% span" refers to how fast a module can adjust its output when a step signal is applied at the input, where the magnitude of this step input is 90% of the input span of the module.
Should I ground my sensor wire shield to the 10-32 ground post on the SCMPB01?
It is not recommended to ground the sensor wire shield to the 10-32 ground post on the SCMPB01 because that is the system side ground, while the sensor wire is on the field side. The sensor wire shield should be grounded to the field side ground, which varies based on the signal conditioner you are using. Please see the "Shield Grounding" application note for more information.
I looked into the SCMVAS-Mxxx modules, but are they truly DC Voltage Attenuators?
SCMVAS-Mxxx modules are actually DC attenuators because they are specified using + and – voltage limits. These are DC voltage levels or peak AC voltages. If they were meant to be AC voltage attenuators, they would be specified in Vrms.
Keywords/Phrases: 5B, 5B module, SCMVAS, SCMVAS-Mxxx, attenuation, high voltage
Can I use an SCM5B module with my OM5-BP-SKT-C?
Yes, any of our SCM5B modules are able to be mounted and operated on Omega's OM5-BP-SKT-C board.
Will the isolation on the SCM5B modules support a discharge of 1500VDC without damaging anything connected to the output?
Yes, the SCM5B modules are isolated up to 1500 Vrms, which means that if the common mode voltage between the field side and system side is limited to 1500Vrms, the device will be protected.
However, the input protection for SCM5B modules (i.e., the voltage across the +IN and -IN input terminals) is 240Vrms max.
How do I convert an RMS voltage to its corresponding peak voltage?
To convert an RMS voltage to its corresponding peak voltage, you simply take the RMS voltage value and multiply it by the square root of 2, or roughly 1.414.
For example, 1500Vrms corresponds to a peak voltage of 1500 * 1.414 = 2121 Vp
If the input range of my signal conditioner is -1V to +1V and the output range is 0 to 10V, does this mean that it ignores polarity?
A signal conditioner with these I/O ranges does not mean that the module ignores the polarity of your voltage input. The output of voltage input modules are scaled linearly, meaning an input of -1V would correspond to an output of 0V, an input of 0V would correspond to an output of 5V, an input of +1V would correspond to an output of 10V, and so on.
Can I use the SCMVAS-Mxxx modules standalone?
SCMVAS-Mxxx modules are high voltage input non-isolated attenuator modules. If used standalone, the module could potentially allow high voltage through to expensive data acquisition equipment. Therefore SCMVAS-Mxxx modules must be used in conjunction with an SCMVAS backpanel and an SCM5B30-07x or SCM5B40-07x isolation and signal conditioning module with input over-voltage protection.
Keywords/Phrases: 5B, 5B module, SCMVAS, SCMVAS-Mxxx
How does the load resistance of a module affect the noise at the output?
Noise at the output of a module is independent of load resistance.
Can I use the SCMXBEFE and SCMXSE accessories to make my SCMPB01/2 DIN rail mountable?
No, converting any of the 16 channel SCM5B backplanes to something DIN rail mountable is a much more involved process than the SCMPB03/04. If you would like a 16 channel SCM5B backplane that can mount on a DIN rail you must purchase an SCMPB01-2, SCMPB01-3, SCMPB02-2 or SCMPB02-3.
What is the maximum channel count for an SCMVAS system?
The largest backpanel for the SCMVAS modules is the SCMVAS-PB16 which has 16 channels. Multiple backpanels can be purchased if more channels are needed.
Is the SCM5B40-06 sensitive to being soldered into a board? Would soldering it damage the part?
We do not recommend soldering the SCM5B pins to a board as it could potentially damage the module. Soldering the pins would also void the warranty.
Many sockets are available which accept the mounting pins. TE Connectivity / AMP part number 50865-5 is an example of these sockets and any equivalent part will work as well.
What types of DIN rails does the DIN rail mounting of the SCMPB04 attach to?
The DIN rail mounting of the SCMPB04 can mount to DIN rail types EN 50022-35x7.5, EN 50022-35x15, EN 50035-G32. These can be purchased as part numbers SCMXRAIL1-XX, SCMXRAIL2-XX, pr SCMXRAIL3-XX where XX is specified as the length of the rail in meters.
Can the DIN rail mounting hardware be easily removed from the SCMPB04?
Yes, the DIN rail mounting hardware for the SCMPB04 can be easily detached and reattached from the board.
Is there a smaller version available of the 8 channel SCMVAS backplane, the SCMVAS-PB8?
The SCMVAS-PB8 is the smallest available backplane for the SCMVAS module series. If you are looking for a small channel count, you may be able to find a suitable custom module in another product line with smaller backplanes that can handle high voltages in our Custom Product List.
Is the SCMXPRT-003 DIN rail mountable?
The SCMXPRT-001 has an option for DIN rail mounting (part number: SCMXPRT-001D) but the SCMXPRT-003 does not. Instead, it can be mounted on the SCMXRK-002 which is a 19 inch metal rack for mounting the SCMXPRT-003 as well as various Dataforth backpanels and the SCMXIF interface board.
Can the SCM5B33 be used in the SCMVAS system?
It is possible to use the SCM5B33 with SCMVAS. However, the output impedance of the SCMVAS-MXXX module at around 14.8k will be loaded by the input 1Mohm input impedance of the SCM5B33-02. This results in an approximate -1.5% positive full scale error.
Do I need to purchase the SCMXCJC with my SCMPB03?
No, the SCMPB03 comes with the CJC built into the backpanel.
What does it mean when an input module has for example a 3kHz bandwidth?
A 3kHz bandwidth on an input module means it can accept voltages from DC to 3000Hz. Any frequency higher than that and the signal will start to be attenuated by the filter at the input.
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