Zener Barrier Z787

Datasheet excerpt: Technical data of  Z787

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
Conformity
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	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
Supply
	Maximum safe voltage	250 V
Series resistance		min. 301 Ω
Certificate		TÜV 99 ATEX 1484 X
	Marking	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
	Approved for	[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 www.pepperl-fuchs.com.

Documents: Z787

CAD+CAE: Z787

Approvals+Certificates: Z787

Function: Z787

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.