Product Overview: MTL3045

Designed specifically for I/P converter applications, the MTL3045 is a single-channel isolated current repeater. This unit receives a 0-20mA or 4-20mA control signal from a safe-area controller. It then passes an identical current signal to drive loads up to 800Ω in the hazardous area. With output capability reaching 16V at 20mA, most I/P converters receive sufficient power. Consequently, this device is essential for pneumatic valve control in intrinsically safe systems.

Technical Specifications

The MTL3045 accepts I/P converters located in Zone 0, IIC, T4–6 hazardous areas with suitable certification. For North American installations, the unit also supports Division 1, Group A hazardous locations. Input resistance is ≤200Ω, creating only a 4V drop at 20mA. This low voltage drop minimizes burden on the control system output. Furthermore, the output resistance exceeds 2MΩ for true floating operation.

• Number of Channels: One, fully floating

• Input Signal Range: 0 to 20mA (including 4-20mA)

• Output Signal Range: 0 to 20mA (identical to input)

• Input Resistance: ≤200Ω (4V at 20mA)

• Maximum Load Resistance: 800Ω (16V at 20mA)

• Output Resistance: >2MΩ

Maximum current consumption for the MTL3045 reaches 90mA across the 20-35V supply range. Typical consumption is only 65mA at 24V for normal operation. Power dissipation within the unit is 1.5W typical at 24V with a 20mA signal. At 35V under full load, however, maximum power dissipation reaches 2.3W. The unit includes a replaceable 125mA, 5x20mm glass fuse (semi-time-lag type M).

Signal Transfer Performance

Excellent transfer accuracy is delivered by the MTL3045 for precise current control. At 20°C, accuracy is better than 20µA for reliable signal reproduction. Temperature drift measures exceptionally low at less than 1µA per degree Celsius. Therefore, stable operation across varying ambient temperatures is ensured. Moreover, input and output circuit ripple both measure less than 40µA peak-to-peak.

Performance Specifications for the MTL3045:

• Transfer Accuracy: Better than 20µA at 20°C

• Temperature Drift: <1µA/°C

• Input Ripple: <40µA peak-to-peak

• Output Ripple: <40µA peak-to-peak

• Response Time: Settles to within 10% of final value after typically 55ms

• Signal Range: 0-20mA (fully floating input and output)

Most process control loops are well suited by the MTL3045 response time of typically 55ms. The unit settles to within 10% of the final value after this period. Full settling to 99% takes slightly longer but remains acceptable for valve positioning. For faster applications, however, consult the factory for alternative models. The floating design also eliminates ground loop errors completely.

Output Drive Capability

High output capability truly distinguishes the MTL3045 from competing isolators. The unit delivers 16V at 20mA to the hazardous area load. This supports loads up to 800Ω for most I/P converters and position actuators. Meanwhile, the low 4V drop across the input terminals leaves more voltage for the output. Consequently, even high-impedance field devices receive sufficient drive current.

Output Specifications for the MTL3045:

• Maximum Load Resistance: 800Ω (16V at 20mA)

• Output Voltage at 20mA: 16V minimum

• Input Voltage Drop: 4V at 20mA (≤200Ω input)

• Compatible Loads: I/P converters, position actuators, solenoids

• Output Floating: Fully floating, >2MΩ to ground

The MTL3045 output capability ensures compatibility with most industrial I/P converters. Popular models from Rosemount, Foxboro, and Siemens all work reliably. The 16V output at 20mA exceeds the typical 12V requirement of many converters. Even with long cable runs, sufficient voltage remains for proper operation. For loads exceeding 800Ω, consider using the MTL3045B or a different model instead.

Power Supply Requirements

The MTL3045 operates from a standard 20-35V DC industrial power supply. For most installations, the nominal voltage is 24V DC. Typical current consumption is 65mA at 24V under normal operation. Maximum consumption reaches 90mA across the entire supply range. Additionally, a replaceable fuse protects the unit from internal faults.

• Supply Voltage Range: 20 to 35V dc

• Typical Consumption: 65mA at 24V

• Maximum Consumption: 90mA across supply range

• Typical Power Dissipation: 1.5W at 24V with 20mA signal

• Maximum Power Dissipation: 2.3W at 35V with 20mA signal

• Fuse: 125mA, 5x20mm glass, semi-time-lag (M), replaceable

Moderate power dissipation is maintained by the MTL3045 even at maximum load. No external heat sinking is required for normal operation. However, mount the unit with adequate clearance from heat-sensitive components. The fuse is user-replaceable, but only replace it with the specified type. Using a different fuse may compromise safety or damage the unit.

Safety Description

Intrinsic safety parameters for hazardous area installations are carried by the MTL3045. The safety description provides entity parameters for accurate system calculations. Voc (Vmax) is 28V for the hazardous-area output circuit. Isc (Imax) is 93mA for energy limitation. Ca (La) is 300Ω for cable capacitance and inductance considerations. Um is 250V rms or DC for the associated apparatus.

• Voc (Vmax): 28V

• Isc (Imax): 93mA

• Ca (La): 300Ω

• Um: 250V rms or dc

• FM Max Entity Parameters: Voc=28V, Isc=93mA, Ca=0.13µF, La=4.0mH

• Area Classification (IEC): Zone 0, IIC, T4–6

• Area Classification (NEC): Division 1, Group A

When using the MTL3045 in hazardous areas, observe the temperature classification limits carefully. For I/P converters, the unit supports T4 to T6 depending on the device certification. Always verify that the field device meets the required temperature class. The entity parameters must not be exceeded by the connected field device.

Installation Guidelines

Install the MTL3045 on a standard DIN rail inside a safe-area enclosure. Mount the unit vertically for optimal convection cooling. First, connect the safe-area controller output to terminals 1 and 2. Next, connect the hazardous-area I/P converter or actuator to terminals 4 and 5. Finally, apply 20-35V DC power to terminals 13 and 14 for operation.

Key Installation Points for the MTL3045:

• Mounting: Use standard 35mm top hat DIN rail

• Orientation: Mount vertically for optimal cooling

• Clearance: Maintain 25mm minimum from adjacent units

• Wire Gauge: Use 0.2 to 2.5 mm² (24 to 14 AWG)

• Strip Length: Strip 6-8 mm for each terminal

• Torque: Tighten screw terminals to 0.5-0.6 N·m

For the MTL3045, hazardous-area wiring must comply with intrinsic safety standards. Use blue cable for hazardous-area circuits where local codes require. Ensure proper segregation between hazardous and safe-area wiring. Maintain adequate creepage and clearance distances in the enclosure. After installation, verify that the output current matches the input current within specification.

Package Contents

Your purchase of the MTL3045 includes:

• (1) MTL Isolated Current Repeater – MTL3045

• (1) DIN rail mounting clip (factory installed)

• (1) Product documentation leaflet

• (1) Standard anti-static packaging

Frequently Asked Questions (FAQ)

Q: What loads can the MTL3045 drive?
A: I/P converters, position actuators, and loads up to 800Ω are all driven by the MTL3045. It delivers 16V at 20mA to the hazardous area load.

Q: What is the input resistance of the MTL3045?
A: The MTL3045 input resistance is ≤200Ω, creating only a 4V drop at 20mA. Therefore, this low burden suits most controller outputs.

Q: What is the response time of the MTL3045?
A: After typically 55ms, the MTL3045 settles to within 10% of final value. This response time suits most process control valve applications.

Q: What hazardous area zones does the MTL3045 support?
A: The MTL3045 supports Zone 0, IIC, T4-6 hazardous areas per IEC standards. For North America, the unit supports Division 1, Group A hazardous locations.

Q: Does the MTL3045 have a replaceable fuse?
A: Yes, a replaceable 125mA, 5x20mm glass fuse is included on the MTL3045. Use only semi-time-lag (type M) fuses as replacements.