Tadiran Telecom Swift Inverter 9U Service Manual page 59

6. Over or under pressure protection: this protection is a pilot
protection for the "over or under pressure error". When the power
pressure is too high or too low but not so high or so low to reach limit
for shutting down (within 165V-265V), it would limit and lower the
frequency first to reduce the air conditioner's needs for the power to
keep teh air conditioner running. This protection is for the adaption to a
unstable power environment and when there is such protection prompt,
it usually means it is possible for "OVP and UVP error" and the
maintenance personnel shall especially note.
7. Cooling overload protection, indoor high temperature heating
protection and indoor coolign freezing protection are also possible
related to the drift of the resistance value of the sensor.
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