ZENER BARRIERS
ZENER BARRIERS
Simple intrinsically safe EX Zener barriers
A Zener Barrier functions as an intrinsic safety device which restricts voltage and current levels to prevent ignition of flammable gases and dust in hazardous environments. The passive device operates based on Zener diode principles to maintain a secure electrical connection between non-hazardous and hazardous zones.
Components:
- Zener Diodes: In Zener Barriers diodes are the primary component to maintain voltage within safe limits. The Zener diode starts conducting when the voltage surpasses its threshold value which helps maintain the voltage at a secure level.
- Resistors: The circuit employs resistors to regulate the current that flows through it. The current-controlling function of resistors ensures that the energy which enters the hazardous area remains below the atmospheric ignition threshold.
- Fuse: An additional protection mechanism is provided by incorporating a fuse. The fuse will blow during a fault which disconnects the power supply and blocks any possible ignition sources.
How Does a Zener Barrier Work?
A Zener Barrier functions to maintain energy levels below the ignition threshold for hazardous environments. Both voltage clamping and current limiting work together to achieve this protective measure.
Voltage Clamping: The Zener diode works as a parallel connection with the circuit. During typical operations the diode stays in a non-conductive state. When the voltage surpasses the Zener voltage which represents the diode’s breakdown threshold the diode becomes conductive and limits the voltage to a safe level.
Types of intrinsically safe Zener barriers
- Single-channel intrinsically safe barriers for simple signals with EX barrier positive or negative polarization in grounded circuits
- Dual-channel EX Zener barriers for simple signals with positive or negative polarity in grounded circuits
- Intrinsically safe Zener barriers with a feedback diode for 4 – 20 mA current loops
- Zener barriers for alternating or bipolar signals in grounded circuits
- Zener barriers with star connection
Intrinsically safe Zener barriers from the MM 7… series are the simplest type of intrinsically safe interface designed to protect electrical circuits used in explosion hazard zones. For proper operation of the barrier, it is necessary to ground the circuit so that the resistance R < 1 Ohm.
INJBB 7028+ EX Zener barrier
BB 702x+ Intrinsically safe barrier (Zener Barrier) for positive polarity of voltage or current, P12 package.
Single channel+ VE.
JBB 702x- Intrinsically safe Barrier (Zener Barrier) for negative polarity of voltage or current, P12 package.
Single channel– VE.
JBB 712x+ Intrinsically safe barrier (Zener Barrier) for negative polarity of voltage or current, with the possibility
of replacing the fuse, P17 package.
JBB 712x– Intrinsically safe barrier (Zener Barrier) for negative polarity of voltage or current, with the possibility of replacing the fuse, P17 package.
CONNECT:
1…………………+ in/out
7…………………+ in/out Ex
3, 4, 5, 6, 9 ….. GND
• Analog output in the explosion hazard zone:
used, for example, for controlling competitions, position sensors, for controlling and supplying optical or audible signalling devices, and all other devices that are located in the explosion hazard zone.
• Analog input in explosion hazard zones: used, for example, for the transmission of electrical signals from devices that are installed in the hazardous area explosion, e.g. photodiodes, devices with their own power supply, etc.
• Binanry input, resistive input in the explosion hazard zone: it is used for two-wire resistance
measurement of devices that are installed in the explosion hazard zone, such as: temperature sensors, potentiometers, etc. This connection can be easily used for the transmission of binary signals from OC relays, TTL outputs and CMOS.
CERTIFICATES
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INJBB 7048+ EX Zener barrier
CONNECT:
1…………………+ in/out
7…………………+ in/out Ex
3, 4, 5, 6, 9 ….. GND
◦ Analog dual output with positive polarity to zone explosion hazards: they are used, for example, to control valves,position sensors, to control and power supply to optical signalling devices or and all other devices that are placed in the zone explosion hazard.
◦ Analog dual output with negative polarity to the explosion hazard zone: they are used, for example, to control valves, position sensors, to control and power supply to optical signalling devices or and all other devices that are placed in the zone explosion hazard.
CERTIFICATES
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INJBB 7055+ EX Zener barrier
JBB 705x Intrinsically safe barrier (Zener Barrier) for variable or bipolar signals, P12 housing.
Simple AC, low level.
JBB 715x Intrinsically safe barrier (Zener Barrier) for alternating or bipolar signals from possibility of replacing the fuse, P17 housing.
Simple AC, low level. Repleceable fuse.
CONNECT:
JBB 705x, JBB 715x
1 + in/out 1
2 + in/out 2
7 + in/out 1 Ex
8 + in/out 2 Ex
3, 4, 5, 6, 9 GND
- Analog output in the explosion hazard zone: apply to control or power supply variable electrical circuits in the danger explosion hazard zone e.g. audio or video signals, frequency or phase control, bipolar one-way control servo motors, etc.
- Analog input in the explosion hazard zone: applicable to variable transmissions electrical signals from the explosion hazard zone e.g. audio-video signals, data transmission, output from vibration sensors, from devices security measures, etc.
- Three-wire output resistive in the explosion hazard zone: applicable to three-wire measurement resistance from the explosion hazard zone e.g.: temperature sensors, sensors positions, potentiometers, etc.
CERTIFICATES
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INJBB 7278+ EX Zener barrier
CONNECT:
1…………………+ in/out
7…………………+ in/out Ex
3, 4, 5, 6, 9 ….. GND
• Analog output in the explosion hazard zone:
used, for example, for controlling competitions, position sensors, for controlling and supplying optical or audible signalling devices, and all other devices that are located in the explosion hazard zone.
• Analog input in explosion hazard zones: used, for example, for the transmission of electrical signals from devices that are installed in the hazardous area explosion, e.g. photodiodes, devices with their own power supply, etc.
• Binanry input, resistive input in the explosion hazard zone: it is used for two-wire resistance
measurement of devices that are installed in the explosion hazard zone, such as: temperature sensors, potentiometers, etc. This connection can be easily used for the transmission of binary signals from OC relays, TTL outputs and CMOS.
CERTIFICATES
Tab Content
