Ashcroft PT-N7 - Temperature Switches - Manual (Page 2)

ELECTRICAL CONNECTION
Remove top cover, cover unscrews (CCW).
On all units except one with terminal blocks – wire directly to
the switch according to circuit requirements. Units with terminal
blocks – wire directly to terminal blocks as required. Terminals
are marked common, norm open and norm closed.
CONDUIT CONNECTIONS
Two
3 ⁄
4
NPT holes are provided, one fitted with a plug, the other
with a cap. It is recommended that Teflon tape or of her sealant
be used on conduit bushing or plug threads to ensure integrity
of the enclosure. NEMA 7 & 9 enclosures require proper conduit
seals and breathers as per the National Electrical Code.
SETPOINT ADJUSTMENTS
General Considerations – When adjusting temperature con-
trols optimum performance will be obtained if the bulb is fully
immersed. After Initially inserting a bulb into a controlled bath
allow five minutes for stabilization. Whenever setpoint adjust-
ment requires a bath temperature to be varied (such as to
observe setpoint and re-setpoint values) the rate of change In
temperature should not exceed 1°F per minute. Switch opera-
tion should be monitored with a suitable pilot light or meter.
Installation and Maintenance Instructions for
ASHCROFT ® P-Series Snap Action
Switches for Temperature Control
TERMINAL BLOCK
SWITCH A
TERMINAL BLOCK
SWITCH B
2
1
3
2
1
3
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&M009-10012-10/00 (250-2551) AMR 12/07
A B
0
20
40
60
0
20
40
60
Series PT-S Single Switch – Remove front cover, held in place
by two screws. Immerse bulb In a bath at the desired setpoint
temperature. Adjust setpoint by rotating the adjustment wheel
until the switch changes mode. It is desirable to recheck actua-
tion point by varying the temperature of the bath as required
and noting operate and reset values.
Series PT-D Dual Switch – Remove front cover, held in place
by two screws. There are two setpoint adjusting wheels. The
adjusting wheel on the left (labeled A) controls the left switch.
The adjusting wheel on the right (labeled B) controls the right
switch. The switches are set independently.
Note: Control is calibrated at the factory such that for proper
operation switch B setpoint must be set higher than
switch A setpoint.
Immerse bulb in a bath at the desired setpoint temperature.
Adjust setpoint by rotating the adjustment wheel until the switch-
es change mode. It is desirable to recheck actuation points by
varying the temperature of the bath as required and noting oper-
ate and reset values. This must be done for both setpoint A and
setpoint B.
Series PT-A Adjustable Deadband Switch – Remove front
cover, held in place by two screws. The setpoint adjusting wheel
labeled A controls the resetpoint of the switch. The adjusting
wheel labeled B controls the setpoint of the switch.
Note: The units are calibrated at the factory such that for proper
operation setpoint B is always higher than re-setpoint A.
Preset adjusting wheel A to a value less than the desired reset
temperature. Preset adjusting wheel B to a value higher than the
desired setpoint. Immerse bulb in a bath at the desired setpoint
temperature. Adjust setpoint by rotating the adjustment wheel B
until the switch changes mode. Then decrease the bath temper-
ature to the desired resetpoint. Adjust resetpoint by rotating
adjustment wheel A until switch changes mode (resets).
Recheck these points by varying bath temperature.