2026-03-10

How to Connect GE Hydran M2 to Hydran 201Ci Controllers: A Complete Wiring Guide

Technical Guide: Connecting GE Hydran M2 to Hydran 201Ci Controllers

Ensuring effective dissolved gas analysis (DGA) in power transformers requires seamless integration between sensors and monitoring controllers. One of the most common yet critical tasks for field engineers is establishing a reliable supervisory link between the GE Hydran M2 sensor and the Hydran 201Ci controller family.

In this technical bulletin, we break down the wiring configurations and communication settings required to ensure your transformer fault monitoring system operates with peak accuracy.

1. Understanding the Supervisory Link (RS-485)

The connection between the Hydran M2 and the 201Ci controller is established via an RS-485 isolated supervisory link. This protocol is robust in high-interference electrical environments, allowing for a maximum cable length of up to 1,200 meters (4,000 feet).

Key Communication Parameters

Parameter	Fixed Setting / Requirement
Baud Rate	Must match Hydran M2 bps (Selectable via keypad)
Data Bits	8 bits
Parity	No parity
Stop Bit	1 stop bit
Flow Control	None

GE Hydran M2 and 201Ci RS-485 supervisory link wiring diagram

2. Detailed Wiring Diagrams by Controller Model

Depending on your specific Hydran 201Ci revision, the terminal board connections will vary slightly.

A. Wiring for Hydran 201Ci-1 and 201Ci-C

Terminal Group	Function and Connection Path
Terminals 1-4	TDM Out: Connection to T- and T+ (or TDM+)
Terminals 5-8	RS-485 Out: Connection to S- and S+ communication module
Terminals 9-12	RS-485 In: Dedicated supervisory link input

Note: The Hydran 201Ci-1 Controller displays gas levels measured by the Hydran M2 but does not support moisture level display. Full moisture analysis requires host software configuration.

Hydran 201Ci-4 multi-channel controller terminal board schematic

3. Remote Communications and Field Best Practices

Remote Modem Communication

Feature	Technical Requirement
Line Type	Analog Line Only: Connection to digital or PBX systems will damage modems
Comm Mode	Call On Alarm: Requires pre-programming the host computer phone number

Installation Checklist

Priority	Installation Requirement
1. Network Sync	All Hydran M2 sensors must share a uniform Baud Rate
2. Signal Integrity	Always connect the Shield (SH) to prevent data corruption
3. Cable Spec	Use Shielded Twisted Pair (STP) for distances up to 1,200m

GE Hydran M2 sensor and monitoring spares inventory

Looking for GE Hydran Spares?

As a leading supplier of industrial automation and monitoring spares, we maintain a robust inventory of GE Hydran components, including M2 sensors and 201Ci controllers.

Contact our sales team today for a fast quote and technical support!

Share This Article

FaceBook Twitter LinkedIn Tumblr Email

High-Performance Interface and Monitoring Spares for Legacy Systems

GE Fanuc PLC Guide: From Series 90-30 (IC693) to PACSystems RX3i (IC695)

Back