Cleveland Convotherm OEB-20.20 Service And Parts Manual page 63

K57 to the coils of contactor K56 and contactors K55.1 for the upper motor
and K55.2 for the lower motor
◊ The K56 contactor closes sending 220 VAC through the Q56.1 overload to
the motors.
◊ The K55.1 contactor closes completing the high speed circuit to the upper
motor and the upper motor turns at a high speed.
◊ The K55.2 contactor closes completing the high speed circuit to the lower
motor and the lower motor turns at a high speed
◊ The normally closed auxiliary contacts of K55.1, K55.2 and K56 open
preventing the K57 contactor from energizing.
• If the combi fan is in the reduced setting 220 VAC is sent from terminal 6 on
connector X11 through the normally closed auxiliary contacts of contactors
K55.1, K55.2 and K56 to the coil of contactor K57
◊ The K57 contactor closes
(a) 220 VAC is sent through the Q57.1 thermal overload to the motor and
the upper motor turns at a reduced speed.
(b) 220 VAC is sent through the Q57.2 thermal overload to the motor and
the lower motor turns at a reduced speed.
◊ The normally closed auxiliary contacts of K57 open preventing the K55
and K56 contactors from energizing.
• For the first 2 minutes 220 VAC is sent from terminal 4 on connector X11
through the normally closed auxiliary contacts of contactor K5 to the K50
contactor coil
◊ K50 contactor closes and the motor turns CW
◊ The normally closed auxiliary contacts on K50 open preventing the K5
contactor from energizing.
• For 15 seconds the motor is de-energized and allowed to coast.
• For the next 2 minutes 220 VAC is sent from terminal 3 on connector X11
through the normally closed auxiliary contacts of contactor K50 to the K5
contactor coil
◊ K5 contactor closes and the motor turns CCW
◊ The normally closed auxiliary contacts on K5 open preventing the K50
contactor from energizing.
• NOTE: If the door switch (S7) opens by the door opening, then the fan circuit
is de-energized. Then the motor will be pulsed in the opposite direction to
"break" the fan. This is to stop the fan quicker for the operator.
c The hot air heat circuit is energized
• 220 VAC is sent from terminal 3 of connector X12 on the Control Board
(A10) to the coil of Contactors K41 and K61 until the cabinet reaches the set
temperature as sensed at probe B6.
◊ The Contactors K41 and K61 close and he 220 VAC is sent to the outer
elements (E41 and E61)
• 220 VAC is sent from terminal 7 of connector X11 on the Control Board
(A10) to the coil of Contactors K42 and K62 until the cabinet reaches the set
temperature as sensed at probe B6.