Omega Vehicle Security OM5-C manual OM5-WBS, Strain Gage Input Modules, Wide Bandwidth

OM5-WBS

Strain Gage Input Modules, Wide Bandwidth

FEATURES

●INTERFACES TO 100Ω THRU 10kΩ, FULL-BRIDGE, HALF-BRIDGE, OR QUARTER-BRIDGE STRAIN GAGES

●HIGH LEVEL VOLTAGE OUTPUTS

●1500Vrms TRANSFORMER ISOLATION

●ANSI/IEEE C37.90.1-1989 TRANSIENT PROTECTION

●INPUT PROTECTED TO 240VAC CONTINUOUS

●FULLY ISOLATED EXCITATION SUPPLY

●100dB CMR

●10kHz SIGNAL BANDWIDTH

●± 0.08% ACCURACY

●± 0.02% LINEARITY

●± 1∝V/°C DRIFT

●CSA CERTIFIED, FM APPROVED, CE COMPLIANT

●MIX AND MATCH OM5 TYPES ON BACKPANEL

DESCRIPTION

Each OM5-WBS Strain Gage input module provides a single channel of strain gage input which is filtered, isolated, amplified, and converted to a high level analog voltage output (Figure 1). This voltage output is logic switch controlled, which allows these modules to share a common analog bus without the requirement of external multiplexers.

The OM5-WBS modules are designed with a completely isolated computer side circuit which can be floated to ±50V from Power Common, pin 16. This complete isolation means that no connection is required between I/O Common and Power Common for proper operation of the output switch. If desired, the output switch can be turned on continuously by simply connecting pin 22, the Read-Enable pin to I/O Common, pin 19.

The OM5-WBS can interface to full-bridge or half-bridge transducers with a nominal resistance of 100Ω to 10kΩ. A matched pair of bridge- completion resistors (to ±1mV at +10V excitation) allows use of low cost half-bridge or quarter-bridge transducers (Figures 2, 3, 4). The 10kHz bandwidth allows measurement of high speed processes such as vibration analysis.

Strain Gage excitation is provided from the module by a very stable 10V or 3.333V source. The excitation supply is fully isolated, allowing the amplifier inputs to operate over the full range of the excitation voltage. This feature offers significant flexibility in real world applications. Full scale sensitivities of 2mV/V, 3mV/V or 10mV/V are offered as standard. With 10V excitation, this results in ±20mV, ±30mV or ±100mV full scale input range producing ± 5V full scale output.

The input signal is processed through a pre-amplifier on the field side of the isolation barrier. This pre-amplifier has a gain-bandwidth product of 5MHz and is bandwidth limited to 10kHz. After amplification, the input signal is chopped by a proprietary chopper circuit. Isolation is provided by transformer coupling, again using a proprietary technique to suppress transmission of common mode spikes or surges. The module is powered from +5VDC, ±5%.

Special input circuits provide protection of the signal inputs and the isolated excitation supply up to 240VAC.

	+EXC	4		LPF	Isochopper™
Strain								20
		4					LPF
Gage	+In		Surge		Amplifier			VOUT
		6			Pat Pending
		3	Suppression
			and					19
		5
			Protection
						+V	–V	I/O Common
	–In
		2
					Isolated
		3			Excitation	Isolated		22
	–EXC	1			Source			RD EN\
					Computer-Side
						Power
	Backpanel
	Term Block
		1
		2
			+V					17
				Isolated				+5V
							Power
			–V	Field-Side
							Oscillator
				Power				16
								Power
								Common

FIGURE 1. OM5-WBS Block Diagram.

18