Compliance Voltage In Single Drop Current Mode; Compliance Voltage For Single Channel Zener With 22 Awg Cable Installation; Compliance Voltage For Galvanic Isolator With 22 Awg Cable Installation - GE Masoneilan SVI II ESD Installation And Maintenance Manual

Compliance Voltage in Single Drop Current Mode

SVI II ESD requires 9.0 V at 20 mA and 11.0 V at 4 mA. Typical smart devices require MORE
Voltage at higher current. The controller supplying the current has LESS voltage available at
higher current. SVI II ESD is unique in that it requires LESS voltage at higher current, which
compliments the characteristic of the source requiring only 9 V at 20 mA.
Table 32 through Table 34 provide examples of several SVI II ESD installations and compliance
voltage calculation necessary to supply 9 V at 20 mA.
Table 32 Compliance Voltage for Single Channel Zener with 22 AWG Cable Installation
Voltage at SVI II ESD at 20 mA
Drop in single channel Zener barrier with 342 Ohms end to end resistance
Drop in 22 AWG cable, 3000 ft. long (30 Ohms per 1000 feet)
Drop in passive HART
Voltage required at controller
1
Such as MTL HCU16AO
Conclusion: Control system must have a compliance voltage equal to or greater than 17.64 V;
contact the DCS vendor to verify compliance.
Table 33 Compliance Voltage for Galvanic Isolator with 22 AWG Cable Installation
Voltage at SVI II ESD at 20 mA
Drop in 22 AWG cable, 3000 ft. long (30 Ohms per 1000 feet)
Required voltage at Isolator
Voltage available from Isolator rated to drive 22 mA into 700 Ohms
Voltage required at controller
Conclusion: Compliance voltage is not an issue because the Isolator provides all the
necessary voltage.
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Improperly or inadequately grounded installations can cause
CAUTION
noise or instability in the control loop. The internal electronics are
isolated from ground. Grounding the case is unnecessary for
functional purposes but grounding the case may be necessary to
conform to local codes.
®
1
Filter
Not applicable - Isolator
supplies the power
Masoneilan SVI II ESD Installation and Maintenance Manual
9.0 V
6.84 V
1.8 V
0.0 V
17.64 V
9.0 V
1.8 V
10.8 V
13.2 V
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=