Key Technical Specifications
- Product Model: ARND-3110A
- Manufacturer: TMEIC
- Function: DC Motor Field Excitation Control
- Control Type: Analog / PID Regulation
- Input Signal: 0-10V or 4-20mA (Verify Jumper Settings)
- Output Type: PWM / Thyristor Gate Drive
- Protection: Over-current, Over-voltage, Field Loss Detection
- Operating Temp: 0°C to 55°C (Derate above 40°C)
- Mounting: DIN Rail or Panel Mount (Check Bracket)
- Firmware/Rev: Rev A (Check Sticker for Suffix)
Product Introduction
I’ve seen entire mill lines stop because a field supply drifted 2% and the motor couldn’t hold base speed. The TMEIC ARND-3110A is the board that keeps the field current locked in, whether you’re running light or slamming the brakes. It’s an analog regulator, which means no software crashes, just pure hardware feedback loops that react in milliseconds.Engineers keep these on the shelf because when a DC drive field supply goes, you aren’t just losing speed control; you’re risking a runaway motor if the field collapses under load. This board handles the excitation logic and gate firing for the field bridge. It’s not fancy, but it’s proven. Just make sure you check the revision suffix; TMEIC changes gain settings between Rev A and Rev B, and swapping them blindly is a recipe for oscillation.
Quality SOP & Tech Pitfalls
The Lab Report (SOP)
We don’t just plug these in and hope. First, visual inspection for cracked solder joints on the high-current gate drive traces. Then, we hook it to a variable DC supply and a load bank to verify the current limit trip point actually trips at the rated setpoint. We check the isolation resistance between the control logic and the gate outputs with a megger. Finally, we log the serial number and test date.The Engineer’s Warning (Pitfalls)
⚠️ Do not swap this board with power applied. The gate drive outputs are floating, but the control ground is not. I’ve watched a tech arc out a gate transformer because he thought “hot-swap” applied to analog field supplies. It doesn’t. Also, check the potentiometers. If this board has been in a humid mill for 10 years, those trim pots are likely oxidized. If you turn them and the resistance jumps, replace the board; don’t try to clean it.
Installation & Configuration Guide
- Pre-Installation: ⚠️ LOCKOUT/TAGOUT. Verify 0V on the field output terminals. Wait 5 minutes for capacitor discharge. Take a photo of every jumper and pot setting on the old board before removing it.
- Removal: Label the field leads (F+, F-) and the armature feedback wires. Release the DIN clip or mounting screws. Pull straight out; don’t wiggle.
- Installation: Match the jumper settings exactly. If the old board had JP3 closed for 4-20mA, close JP3 on the new one. Seat the board fully and secure the mounting hardware.
- Power-On & Testing: Apply control power first. Check the “Ready” LED. Apply field command slowly while monitoring actual field current with a clamp meter. Verify the feedback matches the command within 1%.
Compatible Replacement Models
| Model | Compatibility Tier | Notes |
|---|---|---|
| ARND-3110B | ✅ Drop-in Replacement | Verify gain pot settings; Rev B may have faster loop response. |
| ARND-3100A | ⚠️ Software Compatible | Lower current rating. Check motor FLA before using. |
| ARND-3120A | ⚠️ Software Compatible | Higher current rating. Safe to use, just oversized. |
| ARND-3110A-R | ❌ Hardware Mod Required | Refurbished core exchange. Requires return of old board. |
Frequently Asked Questions (FAQ)
Can I use this for an AC motor field?
No. This is for DC shunt or separately excited fields. AC synchronous excitation uses a different topology. Don’t even try it.How do I know if this board is bad?
If your motor speed droops under load but the armature current is fine, check the field current. If the field current is dropping or oscillating, and the command signal is steady, the regulator is likely failing.Is the ARND-3110A the same as the 3110B?
Mechanically, yes. Electrically, usually. But the internal gain components might differ. Always copy the pot settings from the old board to the new one.Does this have field loss protection?
Yes. It monitors field current and will trip the drive if it drops below a threshold. Don’t jumper out the protection; you’ll burn the motor.Can I repair this myself?
If you have to ask, no. The gate drive section has high-voltage transients. One wrong probe placement and you brick the control section. Send it to a specialist or buy a verified spare.What’s the lead time if you don’t have it?
We usually have these in stock because mills don’t wait. If we don’t, we can source a tested unit in 3-5 days. Don’t buy untested eBay units for a critical mill drive.Do I need to recalibrate after swapping?
Ideally, yes. Do a quick zero and span check. If the motor runs away at zero command, your zero pot is off. If it won’t reach full field, check your span. It takes 10 minutes and saves 2 hours of troubleshooting later.
