Current(A)
Frequency (Hz)
Trip
Hz reduction
Hz increase
prohibit
Hz reduction
Hz increase prohibit
Hz reduction
Hz increase prohibit
(16)
(15.6)
0
(30)
Example of operation during cooling
The operating frequency upper limits shown in the figure below are established for frequency reduction and
increase-prohibit.
(2) Current control
(230)
(223)
(212)
Trip
5Hz every 30 sec. reduction
2Hz every 30 sec. reduction
No control
Increase
prohibit range
(Hz reduction)
(
°
F)
Compressor discharge temperature
(194)
Within the increase-prohibit range, the range changes
to the Hz reduction range (2 Hz every 30 seconds) if
the compressor temperature rises by 4 °F.
*
Operation starts at (8 Hz), and the start current is less than the normal operating current. This prevents the flickering
of fluorescent lights or television screens that occurs when ordinary A/C units start.
7-2-2. Low Start Current
To protect the compressor coil from overheating, the operating frequency is controlled based on the compressor
discharge temperature.
7-2-3. Compressor Temperature Control
50
