Commissioning
EL34xx
152
Version: 1.5
6.6.5
Common-mode voltage and reference ground (based on
differential inputs)
Common-mode voltage (V
cm
) is defined as the average value of the voltages of the individual connections/
inputs and is measured/specified against reference ground.
Fig. 156: Common-mode voltage (V
cm
)
The definition of the reference ground is important for the definition of the permitted common-mode voltage
range and for measurement of the common-mode rejection ratio (CMRR) for differential inputs.
The reference ground is also the potential against which the input resistance and the input impedance for
single-ended inputs or the common-mode resistance and the common-mode impedance for differential
inputs is measured.
The reference ground is usually accessible at or near the terminal/ box, e.g. at the terminal contacts, power
contacts (cable) or a mounting rail. Please refer to the documentation regarding positioning. The reference
ground should be specified for the device under consideration.
For multi-channel terminals/ boxes with resistive (=direct, ohmic, galvanic) or capacitive connection between
the channels, the reference ground should preferably be the symmetry point of all channels, taking into
account the connection resistances.
Reference ground samples for Beckhoff IO devices:
1. Internal AGND fed out: EL3102/EL3112, resistive connection between the channels
2. 0V power contact: EL3104/EL3114, resistive connection between the channels and AGND; AGND
connected to 0V power contact with low-resistance
3. Earth or SGND (shield GND):
◦ EL3174-0002: Channels have no resistive connection between each other, although they are
capacitively coupled to SGND via leakage capacitors
◦ EL3314: No internal ground fed out to the terminal points, although capacitive coupling to SGND
6.6.6
Dielectric strength
A distinction should be made between:
• Dielectric strength (destruction limit): Exceedance can result in irreversible changes to the electronics
◦ Against a specified reference ground
◦ Differential
• Recommended operating voltage range: If the range is exceeded, it can no longer be assumed that the
system operates as specified
◦ Against a specified reference ground
◦ Differential
Содержание EL34 Series
Страница 1: ...Documentation EL34xx 3 phase energy and power measurement terminals 1 5 2019 09 05 Version Date ...
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Страница 52: ...Mounting and wiring EL34xx 52 Version 1 5 Fig 35 Other installation positions ...
Страница 58: ...Mounting and wiring EL34xx 58 Version 1 5 EL3453 LEDs and connection Fig 40 EL3453 LED s ...
Страница 92: ...Commissioning EL34xx 92 Version 1 5 Fig 86 Incorrect driver settings for the Ethernet port ...
Страница 103: ...Commissioning EL34xx 103 Version 1 5 Fig 105 EtherCAT terminal in the TwinCAT tree left TwinCAT 2 right TwinCAT 3 ...
Страница 130: ...Commissioning EL34xx 130 Version 1 5 Fig 147 Process Data tab SM3 EL3443 ...
Страница 131: ...Commissioning EL34xx 131 Version 1 5 Fig 148 Process Data tab SM3 EL3453 ...
Страница 132: ...Commissioning EL34xx 132 Version 1 5 Fig 149 Process Data tab SM3 EL3483 ...
Страница 160: ...Commissioning EL34xx 160 Version 1 5 Index F802 PMX Guard Settings ...
Страница 183: ...Commissioning EL34xx 183 Version 1 5 Index F802 PMX Guard Settings ...
Страница 205: ...Commissioning EL34xx 205 Version 1 5 Index 1C13 TxPDO assign ...
Страница 214: ...Commissioning EL34xx 214 Version 1 5 Index F802 PMX Guard Settings ...
Страница 242: ...Commissioning EL34xx 242 Version 1 5 Index 1C13 TxPDO assign ...
Страница 259: ...Application examples EL34xx 259 Version 1 5 7 Application examples ...