Ashcroft T700 - Temperature Switches - Manual (Page 2)

B. Remote Mounted Controls
Two types of union bushings are available to install a remote
mounted bulb into a thermowell or other
1 ⁄
2
NPT threaded hole.
A non-pressure tight type consists of a bushing, split grommet
and compression nut. To use this, the bulb is inserted through
the nut and the split grommet is slipped into the capillary
between the compression nut and the bushing. After positioning
the bulb as desired tighten the nut to the bushing. This will lock
the capillary at the desired location. The pressure tight type is
clamped to the bulb after insertion by tightening the compres-
sion nut. To use this, the union bushing is screwed into the
1 ⁄
2
NPT threaded hole. The compression nut and sleeve are slipped
onto the bulb which is then inserted into the union bushing.
The bulb is then positioned and the compression nut is hand
tightened pus 2
1 ⁄
4
turns. This will lock the capillary at the
desired location.
ELECTRICAL CONNECTIONS
Remove cover
T400 Series – two screws hold cover to enclosure
T700 Series – cover unscrews
CONDUIT CONNECTIONS
Note – It is recommended that Teflon
® tape or other sealant be
used on conduit, bushing or plug threads to ensure integrity of
the enclosure.
T400 Series standard – one
3 ⁄
4
NPT conduit hole right side.
T700 Series standard – two 3 ⁄
4
NPT conduit holes with one per-
manent plug. NEMA 7 & 9 enclosures require proper conduit
seals and breathers as per the National Electrical Code.
T400 & T700 series – XJL variation –
3 ⁄
4
to 1 ⁄
2
NPT reducing
bushing supplied.
T400 Series – XJK variation – two
3 ⁄
4
NPT conduit holes.
T400 SERIES
SPDT – Wire directly to the switch according to circuit require-
ments. On controls with pilot lights wire lights according to circuit
diagram on inside of cover. See special wiring instruction tag for
single switches with two pilot lights and dual switches with one
or more lights.
2-SPDT – Dual switching elements consist of two SPDT switches
mounted together in a bracket. Switches are calibrated to have
simultaneous operation within 1% of range either on increasing
or decreasing pressure but not in both directions. Wire directly to
the front and rear switch according to circuit requirements.
Leads are provided on rear switch color coded as follows:
Common –
White
Normally Closed – Red
Normally Open – Blue
When hermetically sealed switch element (s) are supplied, the
lead color coding is as follows:
Common –
White
Normally Closed – Red
Normally Open – Blue
T700 SERIES
SPDT – Wire directly to the switch according to circuit
requirements.
2-SPDT – Wire to front switch terminal block (left) and rear
switch terminal block (right) as marked. Strip insulation
5 ⁄
16
˝,
insert in proper terminal connector and tighten clamping screw
to secure.
ADJUSTMENT OF SETPOINT
T400 & T700 Series – A single setpoint adjustment nut (
7 ⁄
8
˝) is
located centrally at the bottom on the inside of the enclosure.
The bulb of the control should be immersed in a bath at the
desired setpoint temperature. Optimum performance will be
obtained if the bulb is fully immersed. Allow five minutes for
initial stabilization.
As received, the temperature switch will normally be set to
approximately 90% of the indicated range. After stabilization,
turn the adjustment nut until switch changes mode. Direction of
turning is indicated on a label affixed to the inside of the control
enclosure. When setpoint has been achieved raise and lower
temperature to insure that the setpoint is correct.
After installation of the control replace cover to insure electrical
safety and to protect internal parts from the environment.
T450 and T750 VARIABLE DEADBAND SWITCHES
Deadband is varied by rotating the wheel on the precision
switch. When viewed from the front of the enclosure, rotation to
the left increases deadband – rotation to the right decreased
deadband. Letters on the wheel may be used as a reference.
Deadbands obtainable will vary from 0.5% to 9% of pressure
range depending on range segment and type of diaphragm.
ADJUSTMENT OF SETPOINT
As received, the temperature switch will normally be set to
approximately 90% of range. Rotate the wheel on the MICRO
SWITCH all the way to the right; this will provide smallest dead-
band. Increase bath temperature to the required setpoint and
turn the adjustment nut until the switch changes mode. Lower
the bath temperature to reset the switch. Rotate the wheel on
the MICRO SWITCH until the desired deadband is obtained.
The upper setpoint will be changing upward with this adjust-
ment. Lower the bath temperature to reset the switch. Raise the
bath temperature to the desired setpoint and turn the adjusting
nut until the switch changes mode. Lower the bath temperature
and check reset point and deadband.
T428 & T429 MANUAL RESET SWITCHES
Dress wire leads from switch terminals so as not to interfere
with or touch reset button.
Note – As indicated above, adjustment of setpoint is made by
use of
7 ⁄
8
˝ nut. Precision switch element mounting screws and
bracket adjusting screw are factory sealed and should not be
tampered with.
Installation and Maintenance Instructions for
T400 & T700 ASHCROFT ® Snap Action
Switches for Temperature Control
TERMINAL BLOCK
FRONT SWITCH
TERMINAL BLOCK
REAR SWITCH
NC
NO
C
NC
NO
C
© 2007 Ashcroft Inc., 250 East Main Street, Stratford, CT 06614-5145, USA, Tel: 203-378-8281, Fax: 203-385-0499, www.ashcroft.com
All sales subject to standard terms and conditions of sale. I&M009-10006-10/00 (250-2230G) AMR 12/07