Communication Problems; Igbt Integrity Check - Daikin PE-ADDA200 Service And Installation Manual

11.1 Communication Problems

First of all check that chiller controller settings and communication wirings are correct. With chiller powered
off and termination resistors off, the following resistance values should be measured:
Inverter (s) connected to Controller
If the problem persists, there is a possibility that the internal 5V is missing. This voltage is generated by an
internal 24Vdc which is also on CN9. Check that CN9 has 24V. If CN9 has 24Vdc, check 5Vdc: RS485 isolate
supply on the DC-DC converter as indicated in the picture of regulation board shown above. If this is ok,
activate the termination resistance (120 Ohm between Tx+ and Tx-) on the last device of the daisy chain.
If 24Vdc is missing:
1. Remove all connectors on CN8, CN9, CN10, CN11, CN12, CN13 and check CN9 il 24Vdc.
2. If this is still missing, replace the regulation board.
3. If after replacement, 24Vdc is still missing, replace the 40-wire flat cable.
4. If after replacement, 24Vdc is still missing, replace the power board.

11.2 IGBT integrity check

Each inverter is made of three IGBT module placed on the refrigerant cooling plate. Each module is a series
of two IGBTs and two diodes, in anti-parallel to them . The c ouple IGBT /diode is c alled " top" i f connected
directly to the pos i ti ve (+540V ) dc bus ; otherwi s e i t is called " bottom" .
In most cases an IGBT failure is accompanied by a diode failure; therefore a diode integrity check through
a multimeter is a simple way to check the IGBTs.
Daikin Applied Europe S.p.A
SERVICE and INSTALLATION MANUAL
Compressor Inverter PE-ADDA200
Tab. 18
Tx/Rx+ to TX/Rx-
1
2
Fig. 32 Integrity check schematics
Page 49 of 51
Tx/Rx+ to GND, Tx/Rx- to GND
40 kOhm
20 kOhm
Rev. 0.3
20 kOhm
10 kOhm