Electrical Connections; Instrumentation; Models Hrd56 Through Hrd3250; Models Hrd56Em Through Hrd3250Em - Sigma HRD Serie Manual De Instrucciones

Electrical Connections

The dryer is prewired, ready for use. Connect the dryer
to the power supply specified on the data plate. Con-
nections, marked L1 and L2, are on a terminal strip in-
side the electrical box. Make connections through the
plugged hole (identified by a tag) on the bottom right
of the box.
DANGER
Ground the dryer using the connection
supplied inside the electrical box. Refer to the
electrical schematic at the back of this manual
for connection details.
Important Note: Do not switch power to the dryer
on and off via a remote disconnect. To avoid dryer
malfunction, power to the unit must be switched on
and off using the switch on the dryer control panel.

INSTRUMENTATION

The following instrumentation helps in monitoring
dryer operation and performance. Instruments which
are available on either the HRD or HRD-EM (energy
management) are so noted.

Models HRD56 through HRD3250

HRD Series dryers are rated NEMA 1 and include fol-
lowing:

• Power ON light

• Vessel pressure gauges

• Purge flow indicator

• Switch-Failure Alarm

• Moisture Indicator

Models HRD56EM through HRD3250EM

HRD-EM Series dryers are rated NEMA 4 and include
the following:
• Power ON light
• Vessel pressure gauges
• Purge flow indicator
• Switch-Failure Alarm
• High-Humidity Indicator
• Compu-Purge
• Digital Display
• Moisture Indicator
• Audible alarm with auxiliary contacts
1-6
Power ON Light
The power ON light on the control panel indicates
when the dryer is turned on and operating.
Vessel Pressure Gauges
A gauge mounted on the gauge bracket indicates
which vessel is onstream and which is regenerating.
The gauge for the onstream vessel indicates operating
pressure; the gauge for the regenerating vessel indi-
cates 0 psig.
Purge Flow Indicator
A gauge mounted on the gauge bracket of the dryer in-
dicates purge air pressure as an approximate measure
of purge airflow when used with the calibration graph
shipped with the dryer. To approximate purge airflow,
locate the pressure gauge reading (psig) on the hori-
zontal axis of the graph. Follow the pressure upward
until it intersects the calibration curve. Follow this
point to the left until it intersects the vertical axis. This
point on the vertical axis is approximately the purge
airflow.
Switch-Failure Alarm
Pressure sensors located on each vessel trigger both
audible and visible alarms if a vessel does not depres-
surize at the completion of its drying cycle. A red
light, labeled SWITCH FAILURE, is located on the
electrical panel. A time-delay relay is included sepa-
rately in the dryer packaging. The relay must be
mounted into the electrical panel before start-up. The
electrical schematic at the back of this manual gives
wiring details.
Moisture Indicator
A color-change moisture indicator is shipped sepa-
rately in a moisture-proof bag. The moisture indicator
should be installed in a customer-supplied 1¼-inch
NPT threaded port at the dryer outlet. The indicator is
green when dry. The color changes to yellow when the
relative humidity of the dryer outlet air is approxi-
mately 4%-5%. This indicator is intended only as an
inexpensive means of determining possible dryer mal-
function.

High-Humidity Alarm (HRD-EM only)

A moisture sensor in the dryer outlet manifold moni-
tors the relative humidity of the outlet air. The sensor
triggers audible and visible alarms if the relative hu-
midity of the outlet air exceeds the factory setting. The
audible alarm is located near the control enclosure. A
red light, labeled HIGH HUMIDITY, is located on the
electrical panel. A set-plug adjustment bulb (refer to
Figure 9) is included for use in calibrating the
HRD and HRD-EM Series (Bulletin 378)