Troubleshooting
9. Operation of the red and
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The red and yellow LEDs (light emitting diodes) on the indicator panel
show when the Series 2300 hot melt system is operating normally and
when it is not. Normally, the red LED remains off while the yellow LEDs
for the tank, hoses and guns are either on, off or flashing. The yellow
LED for a component lights when that component is heating, flashes
when the set temperature for the component has been reached and
goes off when the component has exceeded the set point by more than
2.7.F (1.5.C). -
The LEDs also indicate malfunction and can be used to isolate the
problem. The red LED lights when either of two fault conditions occur in
the tank channel or any of the hose or gun channels:
l When an RTD fails closed (short circuit) or open,
l When another component of the hot melt system fails, allowing any
of the channels to overheat.
The temperature at which the red LED will light may vary from 425’F
(218X) to 475’F (246.C).
A time delay built into the circuitry allows for up to 1 M minutes from the
time the red LED lights in order to troubleshoot before the circuit
breaker trips, shutting off power from the applicator. The circuit breaker
may be switched on again for another l& minutes of troubleshooting
time. The circuit breaker may be reset indefinitely until the tank wall
temperature reaches 450’F (230X). At that point, a close-on-rise
thermostat automatically prevents further attempts to reset the circuit
breaker until the tank wall temperature drops below 45O’F (230X).
Note that on some units, if the tank channel is the faulty channel, the
tank thermostat may cause the circuit breaker to trip before it is tripped
by the solid-state overtemperature protection circuitry on the tank
channel. This is because there is some tolerance overlap in the setpoint
range of the tank thermostat 430’F (221 l C) to 47O’F (243-C) and of the
solid state overtemperature circuitry. If the circuit breaker is tripped by
the tank thermostat, it cannot be reset until the temperature of the tank
wall drops below the setpoint of the thermostat.
See the chart below for a summary of LED operation.
Red LED is
Yellow LED is
The Component
Condition
.
(tank, hose, gun)
OFF
ON
Is heatinq
Normal
OFF
Flashing
Is at the set point
Normal
OFF
OFF
Is sliqhtly above set point
Normal
OFF
ON
Is not heating (is cold)
Abnormal
ON
ON
Has an RTD that has
Abnormal
failed closed (short)
ON
OFF
Is overheating (above
Abnormal
I
1 425’F /22O’C) or it has an I
I
I
1 RTD that has-failed open* 1
l Further troubleshooting required to determine which of the two fault conditions exists.
PM 106 701A
41-23OOSP- l/94
0 Nordson Corporation 1994
Atl Rights Reserved
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