Hood theory of operation (std w/fs) – XLT XD-9007A (ELEC Oven Version – C, AVI Hood Version – C) User Manual

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HOOD THEORY OF OPERATION (STD w/FS)

CS - The Current Sensor is a device that detects electrical current in a wire, and then generates a
signal proportional to it. It drives an LED indicator lamp (LT3) to indicate that the fan is drawing
current and operating. A minimum of 1.5 VAC is required.

LT1 & LT2 - These are standard incandescent light bulbs, and should illuminate when the con-
tacts of S1 are closed.

LT3 – This is a green LED indicator that is driven by the CS to indicate that the fan is drawing
current and operating.

M1 – The Exhaust Fan Motor is a 3-phase, direct drive motor. In normal operation, it is powered
by the VFD through R6, and it’s RPM will vary as the frequency from the VFD varies. There are
no user serviceable parts in the motor, and the bearings are permanently lubricated.

M2 & M3 – The Cooling Fan Motor is a 1-phase, direct drive motor. In normal operation, it is
powered through R1. These fans are used to keep the control box for the hood cool. There are no
user serviceable parts in the motor, and the bearings are permanently lubricated.

PLUG 1, 2, & 3 – These are circular electrical plugs on one end of the Switch Relocation Cord
(SRC). The Plugs connect to Receptacles 1, 2, & 3 on the bottom of the Hood Control Box. The
other end of the SRC plugs into the oven wire harness, and eliminates the operator switch supplied
in the oven. Conversely, when the operator switch on the hood is turned off, the corresponding
oven is turned off as well.

R1 – Is a SPDT relay, which is a electrically operated switch. It uses an electromagnet to operate
a switching mechanism. Line voltage is supplied from the VFD and current flows through a coil in
the relay, causing the contacts in the relay to close. This will complete a circuit for the M2 & M3
to activate and turn on.

R2 – Is a SPDT relay, which is a electrically operated switch. It uses an electromagnet to operate
a switching mechanism. No line voltage is supplied from TS2 via R3 until the fire alarm is acti-
vated. Once fire alarm is activated voltage is supplied to the coil in the relay, causing the contacts
in the relay to close. This will complete a circuit between terminal 1 and 5 on the VFD activating
the VFD to turn on to full speed.

R3 – Is a SPDT relay, which is a electrically operated switch. It uses an electromagnet to operate
a switching mechanism. No line voltage is supplied from TS2 to R3 until the fire alarm is acti-
vated. Once fire alarm is activated voltage is supplied to the coil in the relay, causing the contacts
in the relay to switch from NC to NO. This will interrupt the circuit in the relay supplying voltage
to the lights, the ovens and the cooling fans, the MUA will shut down and the exhaust will run at
full speed.

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