10

AS-Interface Components

EB3C Relay Barrier

Precautions for Operation

4. Output Specifications

(1) When wiring the output from the EB3C, connect the non-

intrinsically safe circuit to terminals A and C. The EB3C out-

put circuit is not equipped with short-circuit protection. If

required, provide a protection in the external circuit.

(2) Relay Output

Some types of loads generate reverse emf (such as sole-

noids) or cause a large inrush current (incandescent

lamps), resulting in a shorter operation life of output relay

contacts. The operation life of contacts can be extended by

preventing the reverse emf using a diode, RC, or varistor, or

by suppressing the inrush current using a resistor or RL.

Contacts are made of gold-clad silver. When using at a

small current and a low voltage (reference value: 0.1 mA,

0.1V), test the contact on the actual circuit in advance.

(3) Transistor Output

When connecting a small load, the load may not turn off

because of a leakage current, even though the transistor

output is turned off. If this is the case, connect a resistor in

parallel with the load to bypass the leakage current.

When an excessively high voltage (clamps at 33V, 1W) or a

reverse voltage is applied to the output terminals, the

clamping circuit or output transistor may be damaged.

When driving an inductive load, be sure to connect a diode

across the load to absorb reverse emf.

(4) In the common wiring only types, the output terminals are

not isolated from each other.

(5) When connecting the connector type EB3C’s in parallel,

use one power supply to power the EB3C’s. Do not connect

any wiring to the C1 and C2 terminals.

5. Wiring for Intrinsic Safety

(1) The voltage applied on the general circuit connected to the

non-intrinsically safe circuit terminals of the EB3C relay bar-

rier must be 250V AC, 50/60Hz, or 250V DC at the maxi-

mum under any conditions, including the voltage of the

input power and the internal circuit.

(2) When wiring, take into consideration the prevention of elec-

tromagnetic and electrostatic charges on intrinsically safe

circuits. Also, prevent intrinsically safe circuits from contact-

ing with other circuits.

(3) The intrinsically safe circuits must be separated from non-

intrinsically safe circuits. Contain intrinsically safe circuits in

a metallic tube or duct, or separate the intrinsically safe cir-

cuits referring to the table below.

Note: Cables with a magnetic shield, such as a metallic sheath, prevent elec-

tromagnetic induction and electrostatic induction, however, a non-

magnetic shield prevents electrostatic induction only. For non-mag-

netic shields, take a preventive measure against electromagnetic

induction.

Finely twisted pair cables prevent electromagnetic induc-

tion. Adding shields to the twisted pair cables provides pro-

tection against electrostatic induction.

Minimum Parallel Distance between the Intrinsically

Safe Circuit and Other Circuits (mm)

(4) When identifying intrinsically safe circuits by color, use light

blue terminal blocks and cables.

(5) When using two or more EB3C’s to set up one intrinsically

safe circuit in the common wiring configuration, intercon-

nect two neutral terminals (N1 through N10) on each EB3C

between adjacent EB3C’s in parallel.

(6) Make sure that the power of the EB3C and contact are

turned off before starting inspection or replacement.

Note: For the details of wiring the intrinsically safe circuits, refer to a relevant

test guideline for explosion-proof electric equipment in each country.

*

Load

An

Cn

*: Surge Absorber

Example of Overvoltage Absorption Circuit

Voltage and

Current of Other

Circuits

Over 100A

100A or less

50A or less

10A or less

Over 440V

2000

2000

2000

2000

440V or less

2000

600

600

600

220V or less

2000

600

600

500

110V or less

2000

600

500

300

60V or less

2000

500

300

150

EB3C-3L catalog Page 10 Monday, February 13, 2006 1:44 PM