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B–CB29M – 460 and 575V THREE PHASE – SEQUENCE OF OPERATION
1- In 460 volt units, line voltage is routed to transformer
T1 and blower motor B3.
2- In 575 volt units, line voltage is routed to transformer
T26. Transformer T26 supplies 460VAC to transformer
T1 and blower motor B3.
3- T1 supplies 24VAC through door interlock switch S51
to terminal strip TB1, which supplies 24VAC to the
indoor thermostat and electric heat, if used.
HEATING
4- When there is a call for heat, W1 of the thermostat
energizes the electric heat blower relay K36 (covered
in the electric heat section).
5- Blower motor B3 is energized on heating speed after
K36-3 closes (see electric heat).
6- The economizer, if used, is energized after K36-2
closes (see electric heat section).
COOLING
7- When there is a call for cooling, G of the thermostat
energizes blower relay K3 and the economizer, if
used. See electric heat for economizer.
8- K3-2 closes energizing blower motor B3 on cooling
speed.
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