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Alarm Switch (Signals)
Notes for Fig 1 Single channel interface circuit
1 Electrical equipment connected to associated apparatus should not use or generate more than 250
volts
2 Installation shall be in accordance with the manufacturer's instructions and Article 504 of the
NEC(ANSI/NFPA 70)
3 For guidance on Installation see ANSI/ISA RP12.6, (Installation of IS Instrument Systems in Class I
Hazardous Locations)
4 Voc or Vt of associated apparatus is less than Vmax Isc or It of associated apparatus is less than Imax
Ci plus capacitance of interconnecting cabling is less than Ca of the associated apparatus
Li plus inductance of interconnecting cabling is less than La of the associated apparatus
5 "Simple Apparatus" is a device that will not generate or store more than 1.2V, 0.1A, 25mW or 20uJ
6 In Div 2 the circuit connected to the switch may be alternatively be Non-incendive in accordance with
NFPA70 Art 500-4(f)(1)
Zone 2 /Division 2
"Alarm": Dry, VFC, SPSTN/O Contact
NI – Ex nA Non-incendive Circuits
V
<254 V ac rms
max
I
< 1 A
max
Zone 1 or 2 / Division 1 or 2
IS – Ex i circuits
U
= 30 Vdc
max
I
0.7 A
max
Hermetically Sealed Switch
Ex m IIC T4 Gc
V
=254 Vac rms
max
I
0.7 A
max
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