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GROUND FAULT PROTECTION
All HHS heater circuits are required to be protected with a ground fault circuit interrupter (GFCI). This device will minimize the risk of
fire or shorting by shutting off the power to the circuit whenever a significant ground-fault current is detected. Suitable circuit breakers
with ground-fault protection can be purchased through nVent.
CONNECTING HHS HEATERS IN PARALLEL
Power Supply
415V Supply
HHS #1
HHS #2
HHS #3
L2 L3
L1
Power Supply
415V/230V Supply
L2 N
L1
3-WIRE, 3-PHASE WITH CONTACTOR
HHS #1
HHS #2
2-WIRE, PHASE-PHASE / PHASE-NEUTRAL WITH CONTACTOR
HHS SYSTEM CONTINUITY AND ELECTRICAL INSULATION RESISTANCE (MEGGER) TESTS
Continuity of each heater should be checked upon removal from packaging and again after installation. Verify that the measured
resistance in ohms agrees with the value printed on the label (with a +/- 10% measured resistance tolerance at 20ºC). Electrical
insulation resistance (IR) should be checked on each heater unit after installation; measure the resistance between the heater element
lead wires and a nearby ground point (e.g., metal heater cladding or welded stud on the hopper wall) at 500 VDC for 1 minute. All IR
values should be greater than 20 megaohms.
IMPORTANT: Ground fault protection devices, although required are not normally displayed in typical single or parallel
wiring diagrams similar to those shown above. Contactors in the diagrams shown above should be controlled by a temperature
control device.
HHS SYSTEM PERFORMANCE TESTING
This test verifies that the system is working properly.
1. When the heaters and controls are installed and connected to
power, and the hopper surface is thermally insulated, turn the
circuit breaker on.
2. Set the primary temperature control device temperature about
20°C higher than the maintain / ambient temperature. This
action energizes the heaters.
3. Allow the heater(s) to be powered for about five minutes,
then measure the voltage and current. Note these values
in the maintenance log as a reference for future
maintenance checks.
4. Lower the temperature control device set point to ensure
that the heater shuts off.
5. Switch off.
6. Set the primary temperature control device to the desired
set point.
Summary of Contents for HHS
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