PXI-2567 Switching Capacity

Signal levels through a switch must account for the following specifications:

  • Switching voltage
  • Switching current
  • Switching power

The following figure shows the valid operating range defined by these limits.

Figure 10. Valid Operating Range

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Switching Voltage

Switching voltage refers to the maximum signal voltage that the switch module can safely maintain.

Switching voltage is defined from channel-to-ground and from channel-to-channel. Channel-to-ground is the voltage potential between the signal line and the grounded chassis. Channel-to-channel is the voltage potential between any pair of signal lines within the switch module. This voltage includes voltages across open relay contacts, as well as voltages between adjacent connection terminals.

Note CE compliance marking for measurement and control devices requires compliance to the IEC 61010-1 standard. Switch modules intended for high voltage signals (>60 V DC / 30 V RMS) are rated for Installation Categories as defined in this standard. Installation Categories describe the acceptable transient overvoltages and fault protection necessary for safe operation.

Switching Current

Switching current is the maximum rated current that can flow through the switch as it makes or breaks a contact.

Switching active currents results in arcing that can damage the contacts of electromechanical relays. A minimum current specification indicates the smallest current that can reliably flow through the switch.

Switching Power

Switching power is the limit on the combined open-contact voltage and closed-contact current of a signal in the switch.

Switching Power = Switching Voltage × Switching Current

Switching high-power signals causes high-energy arcing at the electromechanical contacts during actuation, reducing the useful life of the switch.