York YCAS0130 - Manual (Page 126)

126 YORK INTERNATIONAL
FORM 201.19-NM1 (204)
Internally, the (3) on-board C.T.s and internal circuitry
allow the Motor Protection Module to protect against
high motor current as programmed on the Motor Pro-
tec tor dip switches. These switches are set at the fac to ry
ac cord ing to motor specifi cations.
The module also provides phase rotation protection to as-
sure the screw compressor does not rotate back wards.
A single phase protection circuit located in the module
also monitors for a phase imbalance. If phase to phase
current im bal ance exceeds the 17-25% average imbal-
ance thresholds internally set in the module, the Motor
Protector will shut the system down.
Whenever the Motor Protection Module senses a fault,
internal contacts M1-M2 will open, and shut the system
down. These contacts are wired in series with the com-
pressor motor contactor. When the contacts open, the
micro will attempt to start the system 2 more times. Since
the motor contactor sig nal path from the Re lay Out put
Board to the motor contactor is broken by the Mo tor
Protection Module contacts, it will lock the system out
after 3 faults. The Motor Protection Mod ule must then
be re set by re mov ing 115VAC power from the Con trol
Pan el using CB3. After the Motor Pro tec tor is reset, the
in di vid u al sys tem SYS switch (S2-S5) must be switched
OFF and then ON to re set the microprocessor to al low
re start of the sys tem.
Always review the data in the history
buffer when faults occur. Since the
Micro attempts to restart 2 more times
and fails to restart with the M1-M2
contacts open, the Micro will record
the last 2 faults of "Low Curr/MP/
HP". Hence, the third (3rd) history
buffer will show data related to the
true cause. See page 142 for additional
fault data.
Anytime the module faults, a thor ough
in ves ti ga tion of the problem should be
per formed be fore at tempt ing to re turn
the system to op er a tion. Fail ure to
per form this in ves ti ga tion could
lead to motor or com pres sor failure.
Always record the number displayed
on the module display before removing
power. Ad di tion al de tails on the Mo tor
Pro tec tion Mod ule can be found on
page 16.
Micro Panel Contents