TESTO 557, Instruction Manual

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8 Tips and assistance
21
8 Tips and assistance
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8.1. Questions and answers
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Question Possible causes/solution
flashes
Batteries are almost empty.
> Change
batteries.
The instrument switches
off automatically. Residual capacity of the batteries is
too low.
> Change
batteries.
uuuu lights up instead of
the parameter display
The permissible measuring range has
been undershot.
> Keep to the permitted measuring
range.
oooo lights up instead of
the parameter display
The permissible measuring range has
been exceeded.
> Keep to the permitted measuring
range.
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8.2. Measurement parameters
Name Description
bar, °C Psi, °F
∆ toh SH Superheating, evaporation pressure
∆ tcu SC Subcooling, condensation pressure
to Ev Refrigerant evaporation temperature
tc Co Refrigerant condensation temperature
toh T1 Measured temperature, evaporation
tcu T2 Measured temperature, condensation
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