Convection Circuit Components - TurboChef NGC-1007 Service Manual

The Convection Circuit provides the high-temperature
airflow required to brown and cook food items.

CONVECTION CIRCUIT COMPONENTS

The following is a description of each component
within the Convection Circuit and how each acts
within the circuit. Figure 37 below shows a block dia-
gram of the Convection Circuit.
Main Convection Heater
The main convection heater is an open-coil style
heater rated at 3300 watts at 208 VAC with a resist-
ance of 13.11 Ohms. The convection heater
is controlled by the K4 solid state relay.
Convection Motor
The convection motor is a brushless AC switch reluc-
tance type. Its top speed is 7100 RPM at 1 HP. The
motor is controlled by a proprietary controller.
MOTOR SPINS
COUNTER-CLOCKWISE
FROM BACK
BLWR
MTR
3 7 : Convection Circuit Block Diagram
F I G U R E
BOTTOM IR CONTROL
WH-28
MAIN HX CONTROL
WH-30
+24
RD-19
SSR
K5 K4
B2 A2
B1 A1
L1
M4 GREEN
4
M3 WHITE
3
240 VAC
M2 RED
2 3 PHASE
M1 BLACK
1
OUT
BMSC
SPD CMD
200-240
3
VAC IN
2
1
GROUND (GREEN)
L2
L1
Motor Controller (BMSC)
The motor controller is proprietary and will only
operate the convection motor described above. The
motor controller is controlled on command from the
I/O control board and a 0-10VDC speed command
from the I/O control board.
High Limit Thermostat
The high limit thermostat is a 250 VAC, 3-pole,
manual reset thermostat with a trip point of 572 º F
(300 º C). The thermostat, which interrupts power to
both the main convection heater and the IR element,
should never operate during normal oven operation.
OT1 - HI-LIMIT
MANUAL RESET
C
NC
32
31
OR540
C
NC
22 21
BL510
C
NC
12
11
RD-24
0-10V 1
BK-25
I/O COM 2
WH-31
ENABLE 3
BK-32
I/O COM 4
OR-9
STATUS OK 5
I/O COM 6
THE CONVECTION CIRCUIT
HX ELEMENT
3300 WATTS
13.1 OHMS
HT520
1
BOTTOM IR
3000 WATTS
14.4 OHMS
2
L2
47