DS3800HCMA1E1G | Full Suffix Mark V Analog Base Board

Description

Product Introduction

The “1E” suffix we covered on the discrete HCIC board makes a return here—and for the same reason: speed of termination. The DS3800HCMA1E1G brings spring-cage push-in terminals to the analog side, along with a field supply fuse rating that handles nearly any loop-powered transmitter configuration you can throw at it. The “1G” suffix bumps the fusing to 2.5A, which is far above the typical 0.5A you’ll find on the “1A” variants. If you’re running a bank of transmitters with high inrush or driving loop-powered indicators in series, this board gives you the headroom to avoid nuisance fuse trips.

We’ve installed these in plants where the analog loops have long cable runs—over 300 meters—and the voltage drop becomes a concern. The 2.5A fusing isn’t about current capacity for the transmitters (they still only draw 20mA each). It’s about handling the inrush when you energize the entire loop, and about allowing larger gauge wiring with lower resistance. We’ve measured loop voltage at the transmitter end dropping below 12V on 0.5A fused boards with long cable runs, causing unstable readings. With the higher fuse rating, you can run thicker wire and maintain your voltage at the sensor. Check your terminal block capacity though—the spring cage on the “1E” accepts up to 2.5mm², which handles the voltage drop issue nicely.

Key Technical Specifications

Compatible Replacement Models

Frequently Asked Questions (FAQ)

Q: Why would I need a 2.5A fuse on an analog board when each transmitter only draws 20mA?
A: The fuse protects the entire field supply rail, not individual transmitters. If you’ve got 8 transmitters at 20mA each, that’s 160mA—well within 0.5A. The problem is inrush on power-up. Some older Rosemount and Yokogawa transmitters have internal capacitors that briefly draw 1-2A when the loop is first energized. The slow-blow 2.5A rides through that. Also, if you’re running long cable runs, the higher fuse rating lets you use larger gauge wire to reduce voltage drop—without worrying about the fuse being undersized for the wire’s fault-current capability.

Q: Does the spring-cage termination on the 1E support stranded wire without ferrules?
A: Technically yes, but we strongly recommend ferrules. Stranded wire without a ferrule tends to splay under the spring pressure, leading to intermittent contact over time—especially in high-vibration turbine environments. We’ve seen this failure mode on boards that were “terminated in a hurry” during outages. The maintenance crew eventually had to re-terminate the entire rack. Use ferrules, or use solid copper wire. It’s worth the extra minute per channel.

Q: Can I use the 1E1G as a direct replacement for a 1A1B if my existing harness is screw-clamp?
A: No, not without re-termination. The terminal block positions are the same, but the spring cage accepts the wire directly, without a screw. You can’t insert a screw-clamp-terminated wire into a spring cage—the screw tab is too large. You’d need to strip the wire and either insert it bare (if stranded) or with a ferrule. We’ve seen plants make pigtail adapters with female spade connectors on one end and bare wire on the other. That works, but adds failure points. Plan for 3-4 hours of re-termination labor.

Q: Does the 1E1G’s field supply fuse protect the transmitter if I short the wiring?
A: The 2.5A fuse will clear a dead short, but 2.5A is a lot of current for small signal wiring. If you’re using 24 AWG for your 4-20mA loops, that wire will heat up significantly before the fuse clears—potentially melting insulation. The fuse is there to protect the power supply and the board, not necessarily the transmitter wiring. If you’re concerned about transmitter protection, use a per-transmitter 0.1A fast-blow fuse in series. The 2.5A is a bus protection, not per-channel.

Q: I need to use a 0-10V signal on one channel and 4-20mA on others. Can the 1E1G handle that?
A: Yes, the per-channel jumper configuration works identically to all HCMA variants. The suffix doesn’t affect signal flexibility. The only difference from the 1A1B is physical termination and fusing. The jumper settings are the same—I position for current, V position for voltage. We recommend double-checking each jumper with a continuity meter before powering up; it’s easy to mis-read the tiny silkscreen on a crowded board.

Q: Is the 25ms scan rate sufficient for pressure control loops on a gas turbine?
A: In most cases, yes. Pressure loops are typically slow—time constants in the seconds. The 25ms scan adds minimal phase lag. The real bottleneck is the PID update rate in the Mark V, which is typically set to 100ms for process loops. The HCMA’s scan rate is faster than the controller’s update frequency. So you’re not losing anything. Where the 25ms matters is if you’re using the analog input for vibration monitoring or speed feedback—which you shouldn’t be, as noted earlier. Use the dedicated high-speed inputs for that.

Q: Do you test the 1E1G’s accuracy before shipping, and what’s the typical drift?
A: Yes, we test every board with a precision current source (Fluke 708) across all channels at 4mA and 20mA, and document the counts. Typical drift from the 0.25% spec is under 0.05% on new boards, though used boards can drift more—especially if they’ve been through thermal cycling. We flag any board that exceeds 0.35% and recalibrate it before shipping. If you’re ordering surplus, ask for the test report. Most suppliers won’t have it; we do. If you’re seeing more than ±5 counts at 4mA or 20mA, your board may need a factory recalibration—which is rarely cost-effective on legacy gear. At that point, you’re better off buying another one.

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