1. Suparule Cable Height Meter: A guide
Jan 2012

2. Suparule Cable Height Meters
Cable Height Meter – an ultrasonic device to check wire clearance to ground and spacing of overhead conductors.
Key Features: Safest - no contact with conductors/wire Simple -  One button- one man operation Easy to use - stand underneath, press the button, and read the measurement Fast - measurements in seconds Accurate - less than 0.5% error in reading

3. Why was the CHM developed?
Low wires are a public safety problem
Many reported accidents with both electrical and telecom wires
Existing measuring methods were not considered safe enough for operators

4. Competitive Instruments
Laser type surveying equipment. (Very expensive, and not application specific)
Fibre-glass hot sticks (frequently breaks, conveys electricity if dirty/wet)
Optical device (inaccurate, cannot differentiate between conductors)
No real competitive instrument to the CHM

5. Ultrasound Measurement
From the cone of instrument, the transducer sends out a burst of sound
The sound ‘bounces’ off the cable, and need to be received in cone, as transducer is at the same time transmitter & receiver.
The CHM clocks the amount of time taken
Calculates distance, based on speed of sound. Adjusts for air temperature.
The microcontroller calculates the distance in either imperial or metric
Instrument Time Echoes from wires

6. How to use of Cable Height Meter
     CHM Operation 
1. Select: M (metric) or I (imperial) at the back
2. Set the CAL mode switch to the WIRE
position.
3. Press the ON key to power
4. Stand directly underneath the conductors(s) to be measured.
5.  Press the MEASURE Key to take measurement. Press the READ key to display each of the stored wire height differences (Stored Measurements).

7. Cable height meter: CAL (Calibration) Mode
The CAL mode switch allows the user to periodically check the unit, to ensure that it is still operating within specification.
For cable height measurement, this switch should be in the WIRE position.
When the switch is put to the WALL (CAL) position horizontal measurements to large objects, e.g. walls, can be taken.
When the unit is first used, a horizontal reading to an object, e.g. wall, from a fixed position should be taken. The reading should be recorded, together with the date. Whenever the unit is to be checked for accuracy, a reading should be taken from the same point, noting the result and date. If the reading is outside of specification, the unit should be returned to Suparule.
Date
Readings

8. Range Specification of the CHM 190-300-600 measures up to 15m (50ft)

9. Range Specification of the CHM 300E-600E measures up to 23m (75Ft)

10. Cable height meters: Model choice
CHM models
300
300E
600
600E
Range (25mm cable min)
3 –15m
(10-50ft)
3 –23m
(10-75ft)
Range (12mm cable min)
Range (5.5mm cable min)
3 –12m
(10-40ft)
Range (2.5mm cable min)
3 –10m
(10-33ft)
No. of wires measured 3 6

11. Just simply stand under the O/H line, center yourself under the conductors and press the button.

12. Reading #1 gives the height to the lowest conductor

13. Reading #2 gives the distance between 1st and 2nd wire

14. Reading #3 gives the distance between 2nd and 3rd wire

15. Reading #4 gives the distance between 3rd and 4th wire

16. The memory stores the measurements so that you can scroll
through them in order to record them on paper etc.

17. By pressing button once, readings of up to 6 conductors are taken provided the wires are all within the ultrasonic beam

18. CHM & Ultrasonic beam
Push Measure button once, provided wires are within the ultrasonic beam.
If not, take a number of readings underneath each of the wire.
Make sure the cone is perpendicular
to overhead wire, as otherwise
reflection will not be received
in cone.

19. CHM Accuracy : Error typically less than 0.5% +/-2digits
If the actual distance being measured is 5m, tolerance of +/-0.5%, the CHM will give a reading between 4.975m and 5.025m
The Number of digits specification is an extra tolerance on the display reading. 2 digits = 10mm. The +2d specification therefore means that a further +/-10mm can be added to the display reading, i.e m and 5.035m.
Accuracy is met when CHM is regularly calibrated. Best practice require a 12 month calibration.

20. CHM Battery Battery Life 50,000 measurements
Battery used: 9V, PP3, non-rechargeable, Alkaline, Long-life (>600mAH)
The cable height meters automatically switch off after 3mn if no buttons are pressed to save battery.
When battery is low, a low battery warning symbol pop up on screen: Need to change the battery.

21. Do & Don’t with CHM Do’s: Don’ts:
· Position the unit on the ground, directly underneath the conductor(s) to be measured.
· Align the unit in the direction of the conductor, with the cone pointing towards the conductor(s).
· The ultrasonic waves need to be sent and received in the cone, so alignment is important.
· Keep the unit dry; if it does get wet, leave it upside down in a warm area
· The unit will work in a humid environment; however, if water gets into the electronics, long-term damage can occur.
Don’ts:
· Avoid clutter.
Too many branches/leaves could confuse the unit, as the ultrasonic waves will bounce back from any obstacles.
· Avoid water.
It can damage the electronics
· Avoid sudden changes of temperature.
The Cable Height Meter takes into account temperature to measure the speed of sound travelling in air. If there are sudden temperature changes, i.e. from a warm car in winter to cold icy ground, leave the unit to adjust for a few minutes.

22. Suparule Cable Height Meters : Get the most out of CHMs
Let temperature settle, otherwise incorrect reading is displayed.
Press measure button until reading is stable. Unit needs to get a clear/clean echo back, to calculate correct distance.
Make sure echo gets back into cone, as otherwise, unit will not display reading. May need to tilt unit to get a reading if overhead wires are sloped.
CHM is not waterproof, so keep unit dry as much as possible. If wet, leave it in a warm place upside down, until dry.
Regular calibration a must to get best accuracy

23. Who uses the CHM? Planners Safety Officers Line Managers
Linesmen / Installers
Contractors
Haulage companies
Regulatory Inspectors

24. Warranty & Repair
The CHM is covered by a 24 month warranty on all parts and labour
Any defective instrument will be replaced free of charge during this period
Damaged or broken instruments will be repaired and charged at cost
Each instrument is pre-set, and calibrated at Suparule
Service contract available, please contact your distributor/suparule.

25. Suparule Cable Height Meters
No better instrument for wire distance measurement
Your key partner to safety
Order NOW