XLT XD-9006A (GAS Oven Version – C, AVI Hood Version – C) - Manual (Page 16)

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HOOD THEORY OF OPERATION (STD w/FS)
R4, R5, & R6 - These are SPDT relays, which are electrically operated switches. They use an
electromagnet to operate a switching mechanism. When S2, S3, or S4 are activated line voltage is
supplied to the coil of corresponding relay switching it from NC to NO. This completes a circuit
for a damper that could be wired into 17,19, or 21 on TS 2. If only one damper is used install a
jumper between 17,19, and 21 to activate damper no matter which oven is on.
REC 1, 2, & 3– These are electrical receptacles, which supply line voltage for the ovens. Each re-
ceptacle should have a 20A dedicated breaker supplied from the buildings electrical panel. Line
voltage to each receptacle is supplied via TS1 and R3. If fire alarm is activated R3 will disrupt line
voltage being supplied to receptacle shutting the oven off.
REC 4, 5, & 6– These are circular electrical receptacles mounted on the bottom of the Hood Con-
trol Box. The switch relocation cord (SRC) connects into these and to main switch in the corre-
sponding oven. This deactivates the switch on the oven and relocates the operation of it onto the
front of the hood.
S1 - This SPST (NO) switch is located on the front of the hood and controls the lights.
S2, 3, & 4 - These DPST (NO) switches are located on the front of the hood and control the ov-
ens, as well as initiating and sequencing the operation of the VFD and damper circuits.
Line voltage is continuously applied to pin 1 of REC 4, 5, & 6, which is connected by a
wire to a contact in S2, 3, & 4. This is shown on the schematic as the lower RH connection point
of S2, 3, & 4. When the switch contacts are closed, shown on the upper LH connection point on
the schematic, power is applied to pin 2 of the receptacles, as well as terminal B of R1, 2, & 3.
Wires also connect terminal B and pin 4 of the receptacles. In essence, S2, 3, & 4 replace the
switches on the ovens, and also energize the coils of R4, 5, & 6, which closes the relay contacts
and sends a control signal to dampers or Make-up Air System.
The other set of contacts, shown as the upper set on the schematic, connect terminal 24 of
the VFD and terminals 4, 3, & 2 respectively. The VFD generates it’s own 24 VDC signal volt-
age, and the switches serve as inputs to the VFD. The VFD outputs user-selected frequencies de-
pending upon the combination of switches that are closed.
TS 1, 2, &3- These are terminal strips, which serves as a connection point for wires.
VFD - The Variable Frequency Drive (VFD) converts the AC supply voltage to DC and then con-
verts the DC to a suitable three-phase frequency source for M1. Incoming power connects to ter-
minals L1, L2, & L3. M1 connects to terminals T1, T2, & T3 through TS1. The VFD generates
it’s own 24 VDC control voltage on terminal P24. S2, S3, & S4 serve as user-controlled inputs
and connect terminals 1, 2, & 3 to terminal P24. User inputs include a <RUN> and <STOP/
RESET> buttons, as well as <UP> and <DOWN> arrow buttons. A complete manual can be
found at
www.xltovens.com .