Cooper Instruments & Systems WTM 502 Wire Tension Meter - Manual (Page 13)

1. No wire calibrations are stored of the same diameter as the wire you are looking to measure, and
2. You do not have sheaves of the same diameter.
If both of these conditions exist, contact Cooper Instruments.
Contact Cooper Instruments to improve accuracy for a specific wire type by calibrating to it.
5.3 Loading Error
A tensiometer works by deflecting the cable, which makes the cable path longer than when a tensiometer
is not installed. When the tensiometer is removed, the wire tension decreases as the cable length is
restored. This effect is known as loading error. The WTM 502 design elongates the cable by a mere 0.08
inch (2mm), making loading errors extremely small.
5.4 Non-repeatability
The WTM 502’s sheave with bearing design provides the best mechanical performance. It is also superior
at detecting tension that is being added or removed.
5.5 Non-linearity
Most three-point tension meters employ only linear characterization and have large errors at the
midpoints (up to 15%). The WTM 502 uses multi-point segmenting to correct for non-linearity, reducing it
to less than 0.2%.
5.6 Wire Characteristics
Creep Every material including steel exhibits creep under load. It will neck down over time,
quite quickly over the first few seconds and much slower as time progresses. A wire
cable also sees creep from the wire spacing and wind. This effect is seen as a
display that drifts lower after it has been clamped in line.
Variations
Material that varies in diameter or shape will have different output at the same
tension
Strands
The best cable assembly is one that is perfectly round, as it will not change contact
geometry with the wire twist. The closer the wire cable cross section appears to be
round, the better the measurement performance will be.
6.0 TROUBLESHOOTING
Problem Possible Cause Solution
Powers on momentarily and
turns off
Low battery
Replace with high quality alkaline
batteries
Low battery
Replace with high quality alkaline
batteries
Batteries installed backwards or no
spring contact
Insure that positive terminal of
both batteries (nub) face inward-
towards the black cap. Check
that spring is attached to the
battery cap.
Does not power on
Software reset
Remove battery cap and reinstall
after one minute. Attempt to turn
poser on again
CF 142 11 V 08/09/05