Calibratioon & Repairs

Our C31 Live Line Tester

The C31 Live Line Tester (LLT) is designed for use on overhead a.c. electrified systems operating at 25kV nominal voltage, to indicate the presence of Traction voltage. The C31 LLT will indicate if a section of overhead line equipment (OLE) is de-energised and if not, what voltage is present.

How it works

The C31 LLT will indicate if a section of overhead line equipment (OLE) is de-energised and if not, what voltage is present.

Active Circuit
The second is an active circuit which is battery powered and it controls:the Red – Green lamp voltage indication. It also performs a system check, a lamp test and battery test every time the tester is turned on, and it warns if the calibration certificate is out-of-date, and it logs test activity for diagnostic purposes.The first is a passive circuit that is powered by the OLE voltage itself, which drives the meter pointer to indicate the precise voltage.​
Passive Circuit
The first is a passive circuit that is powered by the OLE voltage itself, which drives the meter pointer to indicate the precise voltage.​
Independent Circuits
The Cotec LLT is two independent testers in one body. Each one is galvanically isolated from the other so that if one circuit should fail then the other indicator can be trusted to keep operating. Having two independent measuring elements, the user can be sure of the indicated condition as each one confirms the other.​

Maintenance, Repair & Calibration

The C31 Tester and HV Probe contain no user-serviceable parts. Opening the Tester or Probe automatically invalidates the warranty and annual Certification.

A C31 tester requires annual testing, calibration, and certification.​ The HV Probe must be replaced after five years of service. (It should be replaced sooner if its resistance falls outside the range of 40.0 ±5 MΩ (Megohms) as this would generally indicate internal damage.)

If there are any issues with a C31 Tester, Probe or accessories, please contact the team at Cotec to discuss corrective action.

Cleaning
Keep the Tester and HV Probe clean by using a damp cloth and wipe dry with a clean paper towel.  Grease can be removed using a cloth and a mild detergent solution (or methylated spirits) and wiping dry with a clean paper towel.  Never immerse any part of the HV probe in water. ​
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Lubrication
Clean threads (internal and external) and treat occasionally with a very small amount of lubricant such as ‘copper slip’.

Operating Instructions & Pre-checks

The C31 LLT is a piece of safety equipment. Following the instructions and warnings is essential for ensuring the safety of those working on or near high-voltage OLE.

This equipment should only be used by competent, trained personnel. Read these instructions BEFORE use.
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Pre-checks
Operating Instructions

Before carrying the equipment to the trackside:​

  • Ensure the equipment has a valid test certificate. This should be displayed on labels affixed to both halves of the tester and the paper Certificate. Also, ensure that the tester (part ‘A’) and HV probe (part ‘B’) have the same serial number.
  • Visually inspect the equipment for signs of damage, check along the length of the HV probe for any splits or cracks, and check the Aluflex is in good condition and securely fastened
  • Turn on the Tester and ensure it completes the self-test operation correctly (see Start-up & Self-Test, below).
  • Make sure that the equipment is clean and free from any contamination that may be conductive at high voltages.
  • Always use the C31 tester in conjunction with approved operating rods and a Primary Insulator Pole with a valid test certificate.
  • Do not use the C31 tester in extreme wet weather.

    ONLY use if ALL above checks are OK
  1. Before each test, observe the safety advice given above.
  2. Ensure the threads are clean, then screw the hook into the top of the Probe and the Probe into the body of the Tester. Take care, not to cross-thread them.
  3. Attach the Aluflex cable to the Tester at the fastening point below the meter. Ensure that the mating surfaces are clean and that the lug is firmly attached to the tester body.
  4. Insert the standard Primary Insulator Pole (check certificate is in date) then fit the standard operating poles into the bottom of the Primary Insulator Pole.
  5. Fasten the other end of the Aluflex cable firmly to the rail track using the rail clamp, again ensuring that the mating surfaces achieve a good electrical connection. (See the warning above!)
  6. Depress the button at the rear of the meter housing and hold for approximately one second. The C31 will then commence a start-up diagnostic routine. (Full details are described below.) Only continue when the Tester displays a steady green light.
  7. Apply the HV probe to the overhead line by the hook at the tip of the probe. The tester has an over-reach collar that also acts as a rain hood. The over-reach limit is indicated by a fluorescent yellow band at the top of the rain hood.
  8. Take great care not to overshoot the overhead line and contact the metal casing of the C31 as this would cause irreparable damage to the tester. Once applied to the line, the C31 will indicate the precise voltage on the analogue meter, also the LED indication will change over from green to red if the line voltage exceeds 11KV +500V, in accordance with Railtrack specification.
  9. When using the C31 to prove isolation before working on the OHL system, always test on a live conductor first to prove the instrument is working properly, then check again after the line has been isolated.
  10. The C31 will turn itself off after 5 minutes. However, the analogue meter operates from the power in the overhead line and will read continuously for as long as there is power on the line. To prevent overheating do not keep the C31 tester attached to a live conductor for longer than 10 minutes at a time.
  11. HANDLE WITH CARE - When removing the tester from the overhead line, take care not to drop the tester on the ground. Although the gauge is resistant to shock, the instrument's internal movement may be permanently damaged by a heavy impact.

Storage

When not in use place the C31 body back into its protective case (especially during transportation). To protect the male thread (HV probe) from damage fit the red plastic cap.

​Store the Tester in a dry location. If the Tester is not going to be used for a long period, fully charge the batteries before storage and re-charge every six months.

Charging

The C31 Tester contains a rechargeable Nickel Metal Hydride (NiMH) battery pack. The latest Cotec C31 Testers use low self-discharge batteries that maintain a usable level of charge for many months.​

We recommend Testers are charged:
- If a ‘low battery’ has been indicated during start-up / self-test.
- Before a job if the Tester has been shelved for a number of months.
- After completion of a job. The smart chargers supplied with new Testers indicate the level of charge and when the full charge has been reached.
- Older trickle charges give no indication of charge. We recommend an overnight charge be sufficient to achieve a full charge.​
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Full instructions can be downloaded from the following link:

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1 Red Flashing
0 - 25%

1 Red Solid,
1 Red Flashing
25 - 50%

2 Red Solid,
1 Red Flashing
50 - 75%

3 Red Solid,
1 Red Flashing
75 - 100%

4 Green Solid
100%

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