Delta Controls HT01 - Manual (Page 2)

IOM-SENTRY-Ex-A : OCT 2012
www.delta-controls.com
Wiring (continued...)
1 or 2 electrical entries are provided, into which
cable glands can be assembled. The thread type
and size is marked on the enclosure, just below the
connection. Select a suitable cable gland which will
maintain the IP rating of the instrument.
USE ONLY SUITABLY ZONE 1 CERTIFIED
CABLE GLANDS OR STOPPING PLUGS.
CABLE TEMPERATURES MAY EXCEED 80°C.
USE
ONLY CABLES WITH SUITABLE
OPERATING TEMPERATURE RANGE.
Use only certified adaptors for Zone 1/Div 1.
Unused entries are to be fitted with suitably certified
stopping plugs.
The three switch terminals are clearly marked
“NORMALLY CLOSED”, “NORMALLY OPEN” and
“COMMON”.
The following diagram can be used as a guide for
wiring.
OPERATION
Adjustments
Pressure and Temperature Switches are supplied
calibrated at the midpoint of their range and to a
falling pressure or temperature unless otherwise
specified.
To re-calibrate:
1. Isolate the instrument from the process and
power.
2. Slacken the set point lock screw.
3. Using a suitable spanner, rotate the range
adjuster clockwise to increase the set point and
counter-clockwise to decrease the set point.
4. Tighten the set point lock screw.
5. Close the instrument lid and tighten lid lock screw
Note: For accurate setting of Pressure and
Differential Pressure models, a suitable pressure
gauge must be used in conjunction with the above
procedure. Do not attempt to set the switch outside
the scale limits. For Temperature models a suitable
calibrated temperature source should be used.
Though the unit may be set anywhere within its
range, for optimum performance, it is good practice
to have a set point value between 25% and 75% of
span.
The striker screw and lock nut are factory set and
should not be adjusted. Should these parts be
accidentally loosened, please contact Delta for
assistance.
Insert bare wires fully into the terminal block and tighten
securely. Keep wiring tails to a minimum and check that
wires do not interfere with the operating mechanism. Use
the earthing / grounding points provided.
BEFORE CLOSING THE LID:
 ENSURE WIRE IS CLEAR OF ALL
MOVING PARTS.
 ENSURE THAT WIRES DO NOT
TOUCH THE LID AS IT IS CLOSED.
Close the lid, being careful not to trap any wires in
doing so. Securely tighten the M3 lid locking screw
set provided using a 1.5mm hex key.
Each instrument if supplied with a label indicating
product description, product code, approvals, etc, as
shown in the example below.
Example label:
MAINTENANCE
Inspections should be carried out at quarterly to
yearly
intervals depending upon operating
conditions. Isolate the unit from process and power
and remove the lid. Check all terminals for
tightness. Check that cable tails are not fouled or
chafed. Check for internal condensation. Check
that the gasket is seated properly in the lid recess
and is not worn. Keep the enclosure and lid clear of
dust build up. It is recommended that instruments
used to provide an alarm are operated periodically to
ensure they are functioning correctly. If further
maintenance is required seek advice from DELTA
CONTROLS
before attempting repair or
replacement of parts.