Toshiba A90-0132, Service Manual

Page: 122 / 176

122
15
Back-up operation
Emergency operation
When one compressor has failed (back-up set-up of compressor)
Outline
When one of two compressors installed in the outdoor unit fails, take the following action if emergency operation by another
normal compressor is possible.
• NOTE 1:
In the case of single compressor installed unit (6HP), back-up operation by one compressor is unavailable. In
this instance refer to the “Emergency Operation when an outdoor unit has failed” section.
• NOTE 2:
For the emergency operation when the failed compressor is an inverter, the capacity control is performed by
ON/OFF control of fixed-speed compressor.
• NOTE 3:
When motor winding of the compressor fails (Short, etc.), do not set back-up of the compressor because
deterioration of oil will occur.
(Another error in the outdoor unit may be caused.)
Work procedure
(1) First,
turn off the power source of all the outdoor units
which are connected to the system.
(2) The following works are performed to
the outdoor unit
of which the compressor failed.
According to the following table, set DIP switch (SW06) on the interface PC board.
Table switch set-up in compressor back-up
SW06
Bit 1 Bit 2 Bit 3 Bit 4
Initial set-up at shipment from factory OFF OFF OFF OFF
No. 1 compressor (INVERTER) (Front left compressor) has failed ON OFF OFF OFF
No. 2 compressor (FIXED) (Front right compressor) has failed OFF ON OFF OFF
(3) Back-up set-up is now complete. Turn on the power source of all the outdoor units.
When an outdoor unit has failed
In this air conditioner, back-up operation is permissible to both an inverter unit and a fixed-speed unit when an outdoor unit
has failed.
In a system in which two or more outdoor units are connected, perform the emergency operation for failure of outdoor unit
when alarm mode, such as one of the following cases, occurs.
(1) Fault of compressor (Short or when one compressor is not operating)
(2) Fault of pressure sensor (Pd, Ps)/fault of temp. sensor (TD1, TD2, TS, TE, TK1, TK2, TK3)
(3) Fault of refrigerating cycle parts, fan system parts, interface PC board, inverter PC board, electric part system, etc.
CAUTION: Emergency operation should only be completed on 1 outdoor unit per system.