Zener Barrier Z787

Zener Barrier Z787

Mfr.: Pepperl+Fuchs Process Automation

Mfr. Model #: Z787

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  • $249.00
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Zener Barrier Z787

  • 2-channel
  • DC version, positive polarity
  • Working voltage 26.5 V at 10 µA
  • Series resistance max. 327 Ω
  • Fuse rating 50 mA
  • DIN rail mountable
  • With diode return

The Zener Barrier prevents the transfer of unacceptably high energy from the safe area into the hazardous area.

The zener diodes in the Zener Barrier are connected in the reverse direction. The breakdown voltage of the diodes is not exceeded in normal operation. If this voltage is exceeded, due to a fault in the safe area, the diodes start to conduct, causing the fuse to blow. The Zener Barrier has a positive polarity, i. e. the anodes of the zener diodes are grounded.

The Zener Barrier is for evaluation of signals from the hazardous area. The diodes of diode return prevent a current into the hazardous area, therefore the current assumption for intrinsic safety calculations is zero.

Depending on the application, increased or decreased intrinsic safety parameters apply for serial or parallel connection. For the detailed parameters refer to the Zener Barrier certificate. Application examples can be found in the system description of the Zener Barriers.


General specifications
Type DC version, positive polarity
Electrical specifications
Nominal resistance 300 Ω
Series resistance terminals 1, 8: max. 327 Ω
Voltage drop terminals 4, 5: 1.2 V + (36 Ω x signal current)
Fuse rating 50 mA
Hazardous area connection
Connection terminals 1, 2; 3, 4
Safe area connection
Connection terminals 5, 6; 7, 8
Working voltage
Supply loop max. 27 V
Measurement loop max. 26.5 V at 10 µA
Degree of protection IEC 60529
Ambient conditions
Ambient temperature -20 ... 60 °C (-4 ... 140 °F)
Storage temperature -25 ... 70 °C (-13 ... 158 °F)
Relative humidity max. 75 % , without condensation
Mechanical specifications
Degree of protection IP20
Connection screw terminals
Core cross-section max. 2 x 2.5 ... mm2
Mass approx. 150 g
Dimensions 12.5 x 115 x 110 mm (0.5 x 4.5 x 4.3 inch)
Construction type modular terminal housing , see system description
Mounting on 35 mm DIN mounting rail acc. to EN 60715:2001
Data for application in connection with hazardous areas
EU-type examination certificate BAS 01 ATEX 7005
Marking Ex-Hexagon# II (1)GD, I (M1) [Ex ia Ga] IIC, [Ex ia Da] IIIC, [Ex ia Ma] I (-20 °C ≤ Tamb ≤ 60 °C) [circuit(s) in zone 0/1/2]
Voltage 28 V
Current 93 mA
Power 650 mW
Maximum safe voltage 250 V
Series resistance min. 301 Ω
Certificate TÜV 99 ATEX 1484 X
Marking Ex-Hexagon# II 3G Ex nA IIC T4 Gc [device in zone 2]
Directive conformity
Directive 2014/34/EU EN 60079-0:2012+A11:2013 , EN 60079-11:2012 , EN 60079-15:2010
International approvals
FM approval
Control drawing 116-0118
UL approval
Control drawing 116-0139 (cULus)
IECEx approval IECEx BAS 09.0142
IECEx BAS 17.0091X
IECEx marking [Ex ia Ga] IIC , [Ex ia Da] IIIC , [Ex ia Ma] I
Ex ec IIC T4 Gc
General information
Supplementary information Observe the certificates, declarations of conformity, instruction manuals, and manuals where applicable. For information see -

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