16
HOOD THEORY OF OPERATION (W/FS)
When any one of the three oven switches on the Hood User Interface (HUI) are touched
( capacitive touch);
1. The Exhaust Fan Motor (Ml) located on the roof will run.
2. The ovens associated with the corresponding switches will tum on.
The first part of the Theory of Operation explains how electrical power is delivered to the
hood and initial sequences when the HUI switch is turned on. The remainder of the Theory of
Operation section explains the function of components in alphabetical order. These components
are also listed on the schematic.
Power for the hood originates at the building's electrical service panel. Two (2) circuit are
required, one is a single phase high voltage circuit for VFD/Fan circuit that connects to TS I termi
nals I & 2. The other circuit is a low voltage circuit for the lights. The line connects to P3 terminal
9 on HMC and the neutral connects to TS I terminal 5.
HUI mounted on the hood controls lighting, VFD activation, Make Up Air (MUA) activa
tion and oven function. When HUI Light Switch is touched a relay is closed and voltage will go to
lights. When ovens are installed with a hood, the Switch Relocation Cord (SRC) effectively elimi
nates the main switch located on the oven and transfers control to HUI switches on the hood.
When HUI switches are touched a communication signal is sent to the VFD via ModBus signaling
it to tum on to a set frequency, at the same time when HUI2 is activated a relay will allow line
voltage to be carried through the Switch Relocation Cord (SRC) to the oven activating it. When
HUI2-4 are activated the MUA will tum on. The VFD has a built in power supply that is wired to
terminal 01 this puts the VFD in run mode so whenever a power loss is sensed the VFD will start
back up in run mode once power is restored. The NO switch in the fire alarm system in the build
ing needs to be connected to TS I terminals 9 & 10. When the alarm is activated 24 VDC from
TS I 9 will return from the fire alarm system to TS I IO then to HMC P8 to tum off lights, cooling
fans, HUI, MUA, and making both relays RI & R2 switch from NC to NO, causing the VFD to
run at 60 Hz.
CB
- Circuit Breakers are used to protect electrical components. If a CB is tripped, eliminate the
cause and press the front to reset.
HUI
- Hood User Interface contains the factory settings so that the hood will operate with the cor
rect hertz when the correct oven size and number of ovens are selected. The factory settings also
contain a selection for a VFD, Non VFD, type of MUA activation, and for a World installation. A
beeping sound and the display will flash if an alarm occurs. An error message will display at top of
screen on HUI. Touching the "I" button will give a brief description of how to correct the error
(see Figure I). Touching the "Light Bulb" button will tum the light on and off inside the hood.
Touching the "Silver Square" buttons will tum each oven on or off and sequence the operation of
the VFD and the MUA circuits. RS485 cable supplies power and communication between the HUI
and HMC.
Technical Support US: 888-443-2751
S
i
mple
.
Smart.
Technical Support INTL: 316-943-2751
