I.S. DI NAMUR CHARM

Installation notes

This Intrinsically Safe CHARM requires an I.S. CHARM Terminal Block.
This CHARM can sense relay/switch contact closure and supports NAMUR sensors with NAMUR-specified line fault detection levels.
This CHARM can be configured as a pulse count input channel.
This CHARM supports line fault detection for detecting open or short circuits in field wiring when external line fault resistors are used. To use line fault detection you must:
- Enable line fault detection in the configuration.
- Connect the dry contact to a 18 kΩ resistor in parallel for open circuit detection and a .36 kΩ resistor in series for short circuit detection.

Figure: External line fault detection resistors

Table: I.S. DI NAMUR CHARM specifications
Item	Specification
Channel type	Intrinsically safe discrete input: 8 VDC, dry contact; supports NAMUR sensors On/Off detection on the + signal
Detection level for On	>2.1 mA
Detection level for Off	<1.2 mA
Channel impedance	1 kΩ ±10%
Wetting voltage	8 VDC ± 1 V
Optional line fault detection levels	Guaranteed short circuit: <100 Ω Guaranteed good status: 360 Ω to 20 kΩ Guaranteed open circuit: >75 kΩ NAMUR sensor compatible
Optional pulse count input frequency range	0.1 Hz to 10 kHz with 50 µsec minimum pulse width
Channel Isolation	Galvanically isolated according to EN 60079-11, voltage peak value 375 VDC.
Input power requirements	+24 VDC input power: +24 VDC ±10% at 28 mA maximum
CHARM heat dissipation (includes terminal block)	0.57 W

Figure: I.S. DI NAMUR CHARM wiring diagram