Features
■ Low peak clamping voltage even during
■ Cable shields are passed through and
may be either grounded or arc-protected to
ground
■ Vibration-resistant screw-type clamp
terminals
severe current surges
■ Ability to repeatedly protect against high
surge currents up to rated limits
■ Convenient mounting and grounding to any
flat surface or to DIN-1 (TS-32) or DIN-3
(TS-35) rail
■ Flame-resistant epoxy-filled housing
1840 Series – Signal and Dataline Protector
®
The Bourns 1840 Series Signal and Dataline Protectors are designed to protect sensitive electronic circuits and components from damaging
surge voltages and currents. Their extremely fast response and low clamping voltages make them particularly suitable for the protection of sensi-
tive signal and datalines associated with computer, data communication, instrumentation, broadcasting and industrial controls. They may be used
directly with EIA standard interfaces RS-232, RS-422, RS-423, RS-485 and with 4-20 mA and 50 mA instrumentation loops. The Model 1840
Series Signal and Dataline Protectors are fast, rugged and capable of protecting against fast rising voltage transients as well as the severe
current surges associated with lightning discharges, in each case up to rated limits.
Method of Operation
®
The Bourns 1840 Series are heavy-duty, multi-staged protectors. A solid-state 3rd stage protection component intercepts the leading edge of the
surge within sub-nanosecond response time. Within microseconds, a primary stage 3-electrode common chambered heavy-duty gas discharge
tube capable of handling 20,000 ampere lightning currents operates and crowbars the majority of the surge energy to ground. The Model 1840
’
®
also utilizes Bourns TBU High-Speed Protector (HSP) technology as a key 2nd stage. Any current through the protector exceeding 300 mA
®
will cause the TBU HSP to quickly transition into a high impedance state, thus isolating any harmful voltage and/or current from damaging the
protected equipment. The gas discharge tube protector remains in the crowbar state until the surge has passed and line voltages return to safe
®
levels. The TBU HSP then automatically restores the line to normal operation by resetting to a low impedance state. There is no need for
resetting a breaker or replacing a fuse to address a transient surge event.
Application
Protectors are generally placed at each end of a signal, dataline or current loop. In the case of daisy-chain configurations (such as RS-485),
protectors are placed at each node.
®
Related Bourns Protectors
®
For outdoor applications with 1/2-inch NPT ports (such as field-mounted 4-20 mA transmitters), please refer to the Bourns Model 1669 Series
Protector. In this application, the mixed use of a Model 1840 Series Protector at the controller and a Model 1669 Series Protector at the field is
recommended.
Characteristics @ 25 °C
Standard Model
Circuit Diagram
TBU® DEVICE
L1
E1
1840-05
1840-12
1840-24
SOLID-STATE
LOW
VOLTAGE
PROTECTION
Maximum Breakdown Voltage
8 V
15 V
30 V
(L-L) and (L-G)
TBU® DEVICE
L2
E2
E3
SHIELD
SHIELD
Surge Life
SHORTING
LINK
100 Amps 10 x 1000 μsec............................................ 300 operations min.
100 Amps 10 x 1000 μsec............................................ 300 operations min.
500 Amps 10 x 1000 μsec............................................ 50 operations min.
1000 Amps 10 x 1000 μsec.......................................... 10 operations min.
3 kA, 6 kV / 8 x 20 μsec Combination Wave................ 100 operations min.
10 kA / 8 x 20 μsec....................................................... 10 operations min.
20 kA / 8 x 20 μsec....................................................... 5 operations min.
Breakdown Voltage............................................................ See table*
ESD @ 8 kV ...................................................................... 10 operations min.
Shield ARC Protection 6 kV / 3 kA..................................... 5 operations min.
Capacitance @ 1 MHz ...................................................... L/G: 45 pF, L/L: 35 pF
Series Resistance.............................................................. 12 Ω typical
Maximum Load Continuous Current.................................. 220 mA
DC Leakage Current at Rated L/G Voltage....................... < 10 μA
Blocking Current................................................................ 300 mA; typical 450 mA
Signal/Data Attenuation..................................................... 3 db @ 30 MHz with 50 Ω
termination
Asia-Pacific:
Tel: +886-2 2562-4117
Fax: +886-2 2562-4116
EMEA:
Tel: +36 88 520 390
Fax: +36 88 520 211
Operating Temperature...................................................... -40 ºC to +60 ºC
Response Time.................................................................. < 1 μsec
Wire Size ........................................................................... 20 AWG
The Americas:
Tel: +1-951 781-5500
Fax: +1-951 781-5700
*Custom voltages are available upon request. Please visit www.bourns.com/data/global/
pdfs/SMBJ.pdf for custom allowable voltage. Lead-time may be extended for some custom
voltages.
www.bourns.com
Specifications are subject to change without notice.
The device characteristics and parameters in this data sheet can and do vary in different applications and actual device performance may vary over time.
Users should verify actual device performance in their specific applications.
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