WESTINGHOUSE I.L. 41-579.3
INSTALLATION
•
OPERATION
•
MAINTENANCE
INSTRUCTIONS
TYPE TD-52 TIME DELAY RELAY
CAUTION:
Before putting relays into service,
operate the relay to check the electrical connec
tions. Close the red handle switch last when plac
ing the relay in service. Open the red handle
switches first when removing the relay from ser
vice.
APPLICATION
The type TD-52 relay is a de timing relay for
general auxiliary service. It has an overall range of
.05 to 30 seconds. The TD-52 relay consists of two
TD-5 units mounted in a type FT-22 case. This
allows utilization of two completely independent
timing circuits. The relay can be used as the tim
ing relay for zone 2 and zone 3 in the conventional
line distance phase relaying. It can also be used in
breaker failure relaying for two breakers.
CONSTRUCTION
The TD-52 relay consists of a timer T2 unit
and a timer T 3 unit. Each timer unit consists of a
reference voltage circuit, a rheostat (T) and scale
plate, a voltage biasing potentiometer (P), a
printed circuit containing static timing compo
nents, an output telephone relay (TR), and an in
dicating contactor switch (ICS). Timer T2 is con
nected to the lower terminals of the relay, and
timer T3 is connected to the upper terminals of
of the relay. All components of T 2 with the excep
tion of the printed circuit board and voltage regu
lator are mounted on the left-hand side of relay
(front view) of the voltage regulator. The printed
circuit board of the T 2 circuit is the front board
(front view).
REFERENCE VOLTAGE CIRCUITS
The reference voltage circuit provides a fixed
supply voltage to the R-C time delay circuit and
L779529
COMPLETE REVISION
protects the static components from high voltages.
It consists of a silicon power regulator and a series
resistor (Rs). The silicon power regulator (Z) is a
10 watt Zener diode mounted on an aluminum
heat sink. The series resistor (Rs) is a 31/z inch
resistor which is tapped for 24/32 volt de and
48 j 125 volt de relays.
RHEOSTAT AND SCALE PLATE
The rheostat (T2) or (T3) provides a variable
resistance for the R-C time delay circuit. It is of
wire-wound construction, which minimizes
resistance change with temperature. Do not
remove the knob from the rheostat shaft, since it
is not easy to replace the knob in the calibrated
position. The timing scale is non-linear as explain
ed in the section under Printed Circuit.
POTENTIOMETER
The potentiometer (P), provides a biasing
voltage which keeps the silicon controlled rectifier
(SCR) turned off until the capacitor voltage
reaches the potentiometer brush voltage. It is of
wire-wound construction and has a locking nut
which should not be loosened unless the relay is
being re-calibrated.
PRINTED CIRCUIT
The printed circuit contains a diode (D 1)
which protects the static components in case the
relay is connected with reverse polarity, a limiting
timing resistor (RL), timing capacitor (C), a paral
lel resistor (R
p)
which makes the calibrating scale
non-linear, and a silicon controlled rectifier (SCR).
The printed circuit also contains a diode (D2) to
reverse bias SCR, a resistor (Rc) and diode (D3)
to protect the static components from the induc
tive voltage kick associated with the telephone
relay coil, and series diodes (D4, Ds, and 06)
EFFECTIVE DECEMBER 1978
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