Dwyer LDT User Manual
Series LDT Leak/Over-Temperature Detection Relay
Specifications - Installation and Operating Instructions
Bulletin L-42
19/64
(7.54)
1/4
(6.35)
The Series LDT0 is used to monitor the shaft seal and the stator
temperature of a submersible pump to detect a leak or over-temperature
before pump failure. A leak is detected by sensing the status of a float or
conductivity switch installed in the seal cavity. When this resistance drops
below the set sensitivity, the output relay energizes and the LED indicator
illuminates. When the seal failure condition clears, the relay automatically
resets. A normally closed temperature switch mounted on the stator
detects over-temperature. The temperature safety feature incorporates a
bistable relay that retains its position during power loss and latches on until
the remote reset button is pressed. The LDT has adjustable leak sensitivity
from 1 k to 35 k ohm. Installation is made simple with a surface mount
configuration.
Important: Read the following carefully and completely before installing or
connecting LDT units.
Note: DO NOT exceed specified electrical rating. Doing so may result in
damage to control unit and load device.
INSTALLATION
1. Lock out all electrical current to relevant control panel during
installation.
2. Fasten the surface mount LDT unit in a control panel.
3. Make the appropriate connections as shown in the wiring
diagram (Figure A) to the corresponding numbered contacts on
the LDT unit.
4. A 100 k ohm resistor must be connected as shown if
conductive probes are used.
5. Set the potentiometer on face of unit to desired resistance (set
to 1 k for float switch configuration).
6. Resume power to control panel and monitor system for proper
functionality.
MAINTENANCE
Upon final installation of the Series LDT Leak/Over-Temperature Detection
Relay, no routine maintenance is required. A periodic check of the system
calibration is recommended. The Series LDT is not field serviceable and
should be returned if repair is needed (field repair should not be attempted
and may void warranty). Be sure to include a brief description of the
problem plus any relevant application notes. Contact customer service to
receive a return goods authorization number before shipping.
3
(76.20)
(101.6)
3/8
(9.53)
4
3-1/4
(82.55)
3-1/4
(82.55)
4
(101.6)
Ø7/32
(5.56)
#8-32
SPECIFICATIONS
Power Requirement: 120 VAC, 50/60 Hz.
Power Consumption: 4 VA (approximate).
Sensitivity: 1 k to 35 k ohm adjustable.
Temperature Limits:
Operating: -4 to 131°F (-20 to 55°C);
Storage: -40 to 185°F (-40 to 85°C).
Sensor Voltage: 12 VDC.
Switch Type: (2) SPDT.
Electrical Rating: 10 A @ 120 VAC resistive.
Response Times:
Leakage Trip: 1 s.
Leakage Reset: 1 s.
Temperature Trip: 0.1 s.
Indicators: Green LED illuminates under normal operation. Red LED’s
illuminate when leak or over-temperature is detected.
Enclosure: Polycarbonate dust cover.
Mounting: Surface mount.
Weight: 17 oz. (482 g).
Agency Approval: UL 508.
THERMAL
NEUTRAL
HOT
RESET
1 2 3 4 5 6
7 8 9 10 11 12
LOAD
SWITCH
100KΩ
ALARM
COND.
PROBE
THERMAL SWITCH
COND.
FLOAT
5 6
ALTERNATE
CONDUCTIVE FLOAT
SWITCH CONNECTION
Figure A
©Copyright 2007 Dwyer Instruments, Inc. Printed in U.S.A. 10/07 FR# R3-443592-02
DWYER INSTRUMENTS, INC.
Phone: 219/879-8000 www.dwyer-inst.com
P.O. BOX 373 • MICHIGAN CITY, INDIANA 46361, U.S.A. Fax: 219/872-9057 e-mail: info@dwyer-inst.com
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