When the hysteresis function is active, the cycle as seen by thebarrier is the following: the valve is considered open as long as it is not really closed and it remains closed as long as it is not really open. The logic of the recopy can be configured in oneway or the opposite.
This feature is useful to control the 2 position feedbacks of the same valve: the barrier gives the position of the valve with only 1 signal. This can save space, complexity and money on a DCS or a PLC while taking really into account the 2 informations of the valve.
Function “control of line fault”
NAEV30 barriers with this feature are dual channel barriers. Faulty line on a NAMUR proximity switch line (open circuit or short-circuit) is detected and is available on an independent
output on safe side dedicated to the “safety” supervision by a DCS or a PLC.
This feature is highly appreciated when you use capacitive or NAMUR vibrating rods on tank level alarms. By this way you can secure the level alarm overflow.
Function “dual recopy output”
This feature is available on the dual channel barriers called NAEV30-DI2NAP-C024… Each intrinsic safety digital input has dual recopy outputs on safe side :
- the first one is active (22VDC / 0.1A)
- the second one is passive by mean of a free potential contact.
This feature is useful to send a the same time a digital input to a control DCS or a PLC and to send the same information by a second channel to a buzzer or an alarm light.
You can also choose the ‘’P’’ option for the passive outputs : open collector with cut-off power:15V – 60 mV – 0.9VA –350Hz.
Function “frequency input with NAMUR output”
This feature is available on the 2- and 4-channel barriers called NAEV30-DI.N-…-PN. This feature is very useful for the transfer of information in speed rotation measurement. The recopy on safe side is an optoelectronic output to be considered as a NAMUR proximity detector. For the end-user such as a PLC or DCS. NAEV30-DI.N-…-PN is fully transparent..