GE Hydran 201Ti Troubleshooting Practice

GE Hydran 201Ti Smart Transmitter: A Complete Guide to On site Installation, Communication Networking, and Troubleshooting

In the operation and maintenance of high-voltage power transformers, online monitoring of dissolved gases in oil has become the core means of preventive fault diagnosis. The Hydran 201Ti intelligent transmitter launched by GE, combined with the 201Ci series controller, has built a highly sensitive and real-time responsive gas monitoring system. This article is aimed at on-site engineers, systematically reviewing the installation points, controller selection, communication network construction of Hydran 201Ti, and focusing on summarizing common faults and their troubleshooting methods to help users ensure stable equipment operation under complex working conditions.

System composition and core functions

1.1 Hydran 201Ti Intelligent Transmitter

Hydran 201Ti is a small temperature controlled cylindrical shell device that can be directly installed on transformer valves, with built-in gas sensors and microprocessor based electronic units. The shell protection level is NEMA 4X (IP66), suitable for outdoor and industrial harsh environments.

Monitoring gas types:

Hydrogen (H ₂)

Carbon monoxide (CO)

Acetylene (C ₂ H ₂)

Ethylene (C ₂ H ₄)

Measurement principle:

The combination of selective gas permeable membrane and combustible gas detector, combined with dynamic oil sampling system, achieves continuous monitoring of gas in oil.

Measurement range and accuracy (0-2000 ppm H ₂ equivalent):

Accuracy: ± 10% reading ± 25 ppm

Relative sensitivity:

CO：18% ±3%

C₂H₂：8% ±2%

C₂H₄：1.5% ±0.5%

Response time:

The time to reach a 90% step change is 10 minutes, suitable for rapid fault warning.

Output and alarm:

Standard analog output: 0-1 mA (non isolated)

Optional output: 4-20 mA (isolated, 1500V RMS)

Alarm contacts: Gas Hi, Gas Hi Hi, Fail (SPDT type, 60W/125VA)

Environmental adaptability:

Oil temperature range: -50 ℃ to+90 ℃ (optional high temperature adapter can reach+105 ℃)

Environmental temperature: -50 ℃ to+55 ℃

Oil pressure range: 0-700 kPa (vacuum not allowed)

Power supply: 100-230 Vac, ± 10%, 50/60Hz, maximum 350VA

1.2 201Ci series controller

Hydran 201Ti must be used in conjunction with a controller, and there are three main models:

201Ci-1 (Single Channel Controller)

Suitable for monitoring a single transformer, equipped with LED digital display, alarm contacts, analog output, and supports local RS-232 and RS-485 networking.

201Ci-4 (four channel controller)

Up to 4 201Ti devices can be connected simultaneously, supporting channel polling display and independent status LED indication. The optional expansion version provides independent alarm contacts for each channel.

201Ci-C (Communication Controller)

No display and alarm contacts, dedicated to managing up to 4 data streams of 201Ti, serving as a communication gateway between RS-485 network and upper computer.

1.3 Hydran HOST upper computer software

Hydran HOST is a monitoring software based on the Windows platform that supports:

Real time alarm and status monitoring

Upload historical data and display trend graphics

Download and Backup of Configuration Files

Remote firmware upgrade

Supporting operating systems: Windows 3.1/95/98/NT 4.0/2000/XP, hardware requirements: PC with 486 or above, 8-32MB memory, VGA display.

Installation and positioning: key to ensuring measurement effectiveness

2.1 Selection of transmitter installation location

On site experience has shown that the installation location directly determines the system response speed and measurement representativeness. The recommended order is as follows:

Preferred location: The straight section of the cooler return oil pipe, located on the outlet side of the oil pump

The oil flow velocity is high and the mixture is uniform, which can quickly reflect internal faults of the transformer.

Alternative location: Upper fuel injection valve or side wall valve of the fuel tank

Suitable for oil-free or natural circulation systems, but response time may be extended.

Not recommended location: bottom of cooler or oil drain valve

Slow oil flow and easy deposition of aged oil can lead to low or delayed readings.

Installation direction:

The transmitter must be installed horizontally to ensure the normal operation of the internal oil sample dynamic sampling system.

2.2 Valve and Adapter Requirements

Full bore gate valves or ball valves must be used, with an inner diameter of no less than 38mm (1.5 inches).

The standard brass adapter comes with a 1.5-inch NPT external thread.

Optional use of a 1-inch high temperature adapter with fins for high temperature conditions (temperature resistance+105 ℃).

2.3 Precautions for Controller Installation

The controller (201Ci-1/4/C) has a NEMA 4X casing and can be installed outdoors.

It must be installed on a vibration free structure or use a randomly provided rubber damping pad.

The installation height should be based on human eye level view and the cabinet door can be fully opened.

All communication cables must be threaded into metal hoses or hard tubes to resist electromagnetic interference (EMI/RFI).

Practical Communication Network and Wiring

3.1 Communication Port Types and Functions

Port type, location, purpose, maximum length, cable requirements

Supervisory Link 201Ti ↔  Controller sensor data acquisition 1300 m 3 pairs twisted pair (16/18 AWG)+total shielding

Multi machine daisy chain networking between RS-485 controllers, 1300 meters long, with 1 twisted pair (16/18 AWG) and total shielding

RS-232 controller ↔  PC/modem local or remote upper computer communication 15m (standard) DB-9 serial port cable

3.2 Typical Networking Structure

Single machine mode: 1 201Ti → 1 201Ci-1 → RS-232 → PC (Hydran HOST)

Multi channel mode: 4 201Ti → 1 201Ci-4 → RS-485 → Superior controller or PC

Large scale network: up to 128 201Ti → multiple 201Ci-C → RS-485 daisy chain → main control PC

Important Notice:

The power supply for the monitoring link is provided by the isolated+15V power supply inside the controller. External power supply is strictly prohibited on site, otherwise it may damage the optocoupler isolation circuit.

Alarm configuration and logic

Hydran 201Ti supports three-level alarms, which can be configured through the controller:

Gas Hi (gas high limit)

Trigger condition: Gas concentration exceeds the first threshold

Output: Controller panel Hi indicator light on+relay engaged

Gas Hi Hi

Trigger condition: Gas concentration exceeds the second threshold

Output: Hi Hi indicator light+independent relay

Fail (system malfunction)

Trigger conditions: sensor failure, communication interruption, power failure, self-test abnormality

Output: Display screen turned off+analog output reset to zero+Fail relay action

Recommended wiring method:

Connect the dry contacts of all alarm relays to the common alarm panel (hard wired) of the substation, ensuring that alarms are sensed even if the upper computer is turned off or the Hydran HOST is not running.

Common troubleshooting and solutions

5.1 Abnormal high or fluctuating readings

Possible causes, inspection methods, and solutions

Mixing bubbles into the oil sample, observe whether there are bubbles discharged from the sampling port, slowly open the sampling valve to exhaust the bubbles, and ensure a full oil state

Before fully opening the valve, check the position of the gate valve or ball valve. Fully open the valve to ensure smooth oil flow

Compare historical data of sensor membrane fouling, and if it continues to be high, perform sensor cleaning or calibration (using H200i calibrator)

If the oil pressure is too low (close to vacuum), check the system oil pressure gauge and increase the oil pressure to>0kPa to avoid negative pressure sucking in air

5.2 Communication Failure (Supervisory Link)

Phenomenon: The controller displays "Comm Fail" or the corresponding channel has no data.

Troubleshooting steps:

Measure the terminal voltage of the monitoring chain: it should be+15V ± 5% (provided by the controller).

Check cable wiring: Are the three pairs of twisted pair cables reversed (Tx+/Tx - confused)?

Confirm that the cable length does not exceed 1300 meters and there are no intermediate joints.

Check if the shielding layer is single ended grounded (to avoid ground loops).

Replace the test with a spare 201Ti to determine if it is a sensor or link issue.

5.3 Analog output is zero or constant

Fail alarm activation? Check if the controller displays a fault, such as a sensor error.

Range configuration error? Confirm if the output range is set to 0-2000 ppm.

Output options do not match? If 4-20mA is required on-site but a non isolated 0-1mA model is purchased, on-site modification is not possible and must be specified when ordering.

5.4 Alarm relay does not operate

Confirm whether the alarm threshold is set reasonably (such as setting the threshold to 500ppm and the current reading to 300ppm).

Check if the dry contact wiring of the relay is correct (COM/NO/NC).

Measure whether there is voltage at both ends of the relay coil (driven internally by the controller).

5.5 Historical data upload failure (HOST software)

Check if the PC serial ports (COM1 – COM4) are occupied by other programs.

Confirm that the baud rate is consistent (supports 1200/2400/4800/9600).

If using a modem, check the phone number, dialing prefix, and modem initialization string.

Calibration and maintenance recommendations

6.1 Recommended attachments

H200i electronic calibrator: used for on-site verification and calibration of 201Ti electronic circuits, it is recommended to equip at least one at each station.

H201-TW pipe wrench: a specialized tool used for correctly installing sensors to avoid damaging the diaphragm.

6.2 Calibration cycle

It is recommended to perform full-scale calibration every 12-18 months.

If the deviation between gas reading and laboratory oil chromatography analysis exceeds ± 15%, calibration should be carried out immediately.

6.3 Software Upgrade

Through Hydran HOST, the 201Ti embedded firmware can be remotely upgraded without disassembling the device, greatly reducing maintenance costs.