Trane CH530 Installation, Operation And Maintenance Manual page 42

AFD Operation
Figure 24. Motor current signature representing surge
Rectified
Motor
Previous
Current
Sampled
Value
Transitory
Pressure
Breakdown
Interface to Adaptive Frequency Drive
Communications between the chiller control and the AFD
are handled via the Machine Bus ("M-bus") connected to
the RS-485 AFD Comm Interface module. Signals digitally
sent over the M-bus include start, stop, speed change, and
drive faults.
At start of the compressor motor a signal corresponding to
the starting frequency (38 Hz) is sent to the drive.
The digital speed signal is set-up such that the AFD
operates over a 38-60 Hz frequency range.
Figure 25. Chiller control to remote-mounted inverter interface block diagram
Chiller
Control
115/50/60
Power Supply
24 Vdc
24 Vdc
Out
In
To other
LLIDs
Machine Bus
24 Vdc Power
and Ground
Oil Pump
Interlock
42
Present
Sampled
Value
Pressure
Rebuilding
1 Surge
Occurrence
Chiller
Power
4-wire
HPC
Chiller
AFD faults are sent over the M-bus to the UC800 or
DynaView™ controls for communication on the chiller
display.
High Pressure Cutout—The inverter accepts a NC HPC
switch (at terminals 2X1-3 and 2X1-4. In the event of a
chiller high pressure condition, the HPC switch will open
and the drive shall shut down and de-energize the motor.
Output contacts are required to control the load of the oil
pump motor and the cooling circulating pump. The
contacts are normally open, and close when the AFD
energizes the motor.
Time
Note: Unlike locked rotor amps associated with
electromechanical starters, the phase currents are
not expected to rise above 85 percent RLA prior to
1.6 seconds following the sending of the speed
signal, after which they then remain above
85 percent RLA until the compressor motor has
come up to speed.
An "Up-to-Speed" signal must occur before the Maximum
Acceleration Timer times out (plus 15 seconds) or a
MANUAL RESET (MMR) alarm will occur.
The block diagram (see
communication of the starter module to Unit Mounted
Inverter Interface controls interconnecting circuits.
The Oil Pump Interlock load is 115 volts ac, 3/4 hp reset.
AFD
115/50/60
Power
115 Vac
Recomm
Adaptive Frequency™ Drive
115 Vac
HPC
3/4 hp
24 Vdc Sense
AFD
Figure 25, p. 42) shows the
3-phase line
Circuit Breaker
line in with
115 Vac
Motor
Cooling
Pump
AFDK-SVU01C-EN