Backup Operation (Emergency Operation); Note For Backup Operation - Toshiba MMY-MUP0721FT6P-UL Service Manual

9. BACKUP OPERATION (EMERGENCY OPERATION)

This product offers backup modes of operation to tide over certain emergency situations. If a trouble occurs in
one of the compressors, it is possible to operate the system on an emergency basis by operating only the
remaining compressor, (compressor backup operation).
If one of the outdoor units fails in a combined outdoor unit system, the system can be operated on an
emergency basis by keeping only the remaining outdoor unit(s), (outdoor unit backup operation).
Perform backup operation setting in accordance with the procedure described below.

9-1. Note for Backup Operation

The method of backup operation differs according to the contents of trouble as shown in the table below.
Contents of trouble
One of the compressors in the same unit fails (see Note 1)
All the compressors in the same unit fail
A trouble occurs in a compressor motor coil (e.g. a layer short-circuit)
A trouble occurs in a refrigerating cycle part, fan or related part, or electrical part
A trouble occurs in a temperature sensor or pressure sensor
Note 1: If the compressor has failed due to a trouble in its motor coil (e.g. a layer short-circuit), do not perform
compressor backup operation because of severe oil degradation.
Note 2: Keep the number of backed-up outdoor units under compressor backup operation to one in the system
(single refrigerant line).
Note 3 : Keep the number of backed-up outdoor units to one in the system (single refrigerant line.)
Example:
Prohibited
Note 4 : It is possible to do backup operation even the system is connected with different chassis size and different weight
of outdoor units.
Example:
Permitted
Small Chassis
Backed-up Backed-up
Outdoor Unit Outdoor Unit
Failure Failure
Backed-up
Outdoor Unit
Failure
Big Chassis
Method of backup operation
Compressor backup (see Note 2)
Outdoor unit backup or cooling-
season outdoor unit backup (see
Notes 1, 3, 4 and 5)
Backed-up
Outdoor Unit
Failure
Small Chassis
Big Chassis
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Setting procedure
Go to 9-2.
Go to 9-3. or 9-4.