Technical Publication
LOR-1
HIGH SPEED
MULTI-CONTACT LOCK-OUT RELAYS
FOR POWER INDUSTRY
APPLICATIONS
ELECTROSWITCH
SWITCHES & RELAYS
UNIT OF ELECTRO SWITCH CORP.
HIGH SPEED
MULTI-CONTACT LOCK-OUT RELAYS
FOR POWER INDUSTRY APPLICATIONS
ELECTROSWITCH
Weymouth, Massachusetts
ABSTRACT
The Series 24 Lock-out Relays are high-speed (as low
as eight milliseconds) control relays used primarily as
auxiliary relays in applications requiring many contacts (up
to 48). The LOR is an electric-trip and manual-reset device.
The LOR/ER is an electric-trip and either manual or
electric-reset. The LOR/SR is an electric- trip and self-reset
device. All units have mechanical position indicator targets.
They are qualified to ESC-STD-1000, which includes aging
and seismic vibration requirements to ANSI/IEEE 323-1984
and ANSI/IEEE-344-1987 for class IE uses in nuclear
power generating stations.
The testing also satisfies
ANSI/IEEE CJ7.90-1989 and ANSI/IEEE C37.98-1987.
INTRODUCTION
Lock-out Relays of various types are often used in the
electrical power industry. These auxiliary relays are
electric-trip, manual or electric-reset control relays for the
purpose of tripping and locking out circuit breakers or
other devices automatically when a fault or other pre-
determined condition exists. Lock-out-relays are generally
used in conjunction with protective relays to protect
transformers, buses, and rotating machinery in various
electrical systems.
Fig. 2. Series 24 LOR/ER Electric-reset
Lock-out Relay and LOR/SR
Self-reset Lock-out Relay
High-speed, rugged, multi-contact units are needed.
This paper describes a family of Lock-out relays with up
to 48 contacts that operate as quickly as eight
milli-seconds and are seismic shockproof.
BASIC CIRCUIT OPERATION
The control of the Lock-out Relays for operation as a
relay requires no special wiring. They only require a
N.O. contact (Sl) to command the LOR to TRIP and the
Electric-reset LOR/ER needs an additional N.O. contact
(S2) to initiate the command for RESET. The choice of
Sl should take in consideration the burden data of trip
coil, LOR/T, since Sl will "make" this current. This
circuit is self-interrupting with the LOR contacts so Sl
need not be concerned with the "break" of the TRIP
circuit. On the electric-reset LOR, S2 needs to make
only the K1 relay circuit so the burden of the LOR/R does
not affect S2. Any pilot duty device is acceptable for both
S1 and S2.
Lock-out Relay applications often require ten or
more N.O. and N.C. contacts. The relays can be used to
change sequences such as shutting down a faulty pump
and then initiating the action to start-up a standby pump
or bypassing a faulty circuit by opening and closing
breakers.
Lock-out-relays are normally latched in the RESET
position and trip-out to a TRIP position when
commanded. There are then manual-reset, electric-reset,
and self- reset versions to get back to the RESET position.
Fig. 1. Series 24 LOR Manual-reset Lock-out Relay
_
Initial Release – September 15, 1977
Revised – January 3, 1980
Added LOR/SR – February 1, 1983
Revised – March 15, 1985
Revised – April 15, 1987
Revised – June 1, 1991
Revised – February 15, 1993
Revised – February 10, 1994
Revised – September 1, 2012
1
Manual-reset LOR Circuit
Fig. 3. Manual-reset LOR Control Circuit Schematic
(shown in RESET position)
The standard station control bus voltage is used. The
LOR, as shown, is in the RESET position. The LOR/T coil
form represents the linear solenoid that releases the latch that
locks the LOR in the RESET. The mechanical design is
described later under THE ELECTRO-MECHANICAL
DRIVE.
The LOR contacts shown are normally closed in the
reset position. They are within the LOR control package. G
and B are tie points to connect the LOR to the control circuit.
C and F are internal connection points shown for
information.
To command the Lock-out Relay to TRIP, S1 is closed.
This completes a circuit across the LOR trigger solenoid,
which operates, causing the device to snap to the TRIP
position. It locks into this position and remains there
indefinitely. When this happens, the LOR contacts open,
thereby removing the control circuit from the bus.
The unit will stay locked-out in the TRIP position until
manually reset. S1 may be an auxiliary contact – from a
breaker, a protective relay, or from another auxiliary device
like a relay. The condition of the Lock-out Relay is visible
by the handle location and a mechanical target within the
nameplate (Black for RESET, Orange for TRIP)
Electric-reset LOR/ER Circuit
The Electric-reset Lock-out Relay operates from the
control bus voltage like the manual-reset version. The
LOR/ER, as shown, is in the RESET POSITION. The
LOR/T coil form is the same linear solenoid that is used in
the manual-reset LOR, and controls the latch that locks the
LOR/ER in the RESET position. The LOR/R coil form
represents the rotary solenoid that is used to reset the
LOR/ER electrically. Kl is a relay used to control the
rotary solenoid. This enables S2 to be a low level contact.
It controls only the Kl relay coil. The Kl contact operates
the high current rotary solenoid. TB1, TB2, and TB3 are
terminal block connections, and F and H are LOR tie
points – all are for connection to the control bus. G, B, and
TB4 are internal tie points shown for information only.
The command of the LOR/ER to the TRIP position is
the same as with the manual- reset LOR which was
previously described. When tripped, the NC LOR
contact in the LOR/T circuit opens removing LOR/T
solenoid from the circuit. When this happens, the LOR NO
contact in the Kl relay circuit closes enabling this circuit to
be used.
To command the LOR/ER to reset, S2 is closed. This
completes the circuit to the K1 relay and it operates closing
contact K1. This completes the circuit to the LOR/R rotary
solenoid and it indexes to the RESET position. When this
happens, the N.O. LOR contact opens. This opens the
circuit on the K1 relay coil. The K1 relay drops out,
opening contact K1 that opens the rotary solenoid LOR/R
circuit. At the same time, the N.C. LOR contact, in the
linear solenoid LOR/T circuit, closes, setting up the
LOR/ER for the next TRIP command.
Sl and S2 should be momentary contacts and should not
stay closed. If both contacts are closed at the same time, a
"pumping" action will result with the LOR/ER indexing
back and forth between the RESET and TRIP positions.
The handle and target indicators are the same on the
standard electric-reset LOR/ER as the manual reset LOR.
The handle on the high-speed LOR/ER is not an indicator
and remains in the vertical position and the target must
be manually reset (see page 9).
Self-reset LOR/SR Circuits
The self-reset Lock-out Relay operates from the control
bus voltage like the LOR and LOR/ER. The LOR/SR, as
shown in Fig. 5 and 6, is in the RESET position. The
LOR/T coil is the same linear solenoid that is used in all
LOR's, and controls the trigger that locks the LOR/SR in
the RESET position. The LOR/R is the same rotary
solenoid used in the LOR/ER and is used to electrically
reset the LOR/SR. Kl and K2 are two relays with N.O.
contacts used in the control circuit. B-A is a N.O. contact
and E-F-G is a form “C” contact -- both in the control
circuit. F-G is N.C. in the reset position while F-E is N.O.
TB1, TB2, TB3, and TB4 are terminal block connection
points for the user. R1 and R2 make up a bridge circuit on
Fig. 4. Electric-reset LOR/ER Control Circuit Schematic
(shown in the RESET position)
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both the INSTANTANEOUS RESET and the TIME DELAY
RESET units. In addition, the TIME DELAY RESET version
has an additional lE-lF normally open (NO) contact to isolate
the K2 coil plus the time delay circuit, consisting of Rl and Cl-
C2-C3-C4, which are wired in parallel. Dl protects the
capacitors from a possible incorrect polarity hookup.
The INSTANTANEOUS RESET version of the LOR/SR
will reset itself within 80 milliseconds after the fault has
cleared itself (Sl opens). This circuit is illustrated in Fig. 5.
Fig.6. Time-delay Self-reset circuit for the LOR/SR
Operating Voltage
The LOR, LOR/ER, and LOR/SR Lock-out Relays are
direct current actuated auxiliary relays. Because they are only
actuated for short periods of time and are self-interrupting, they
may be subjected to maximum design voltage indefinitely
without exceeding the 50
o
C temperature rise in ambient
conditions as high as 55
o
C. This is using class 105 insulation
and the applied thermo-couple method of temperature
determination.
Fig. 5. Instantaneous-reset circuit for the Self-reset
(shown in RESET position) Lock-out relay
The Lock-out Relays operate reliably over the full
voltage ranges described in ANSI/IEEE C37.90-1989, the
"Standard for Relays and Relay Systems Associated with
Electric Power Apparatus." These ratings are shown below:
TABLE I
Coil Operating Range*
COIL
A, B
C
D, E, G, K
F, H
NOMINAL
VOLTAGE
24 VDC
48 VDC
125 VDC
250 VDC
NORMAL
VOLTAGE
OPERATING RANGE
19.2 to 28 VDC
38.4 to 56 VDC
100 to 140 VDC
200 to 280 VDC
The LOR/SR trips in the same manner as the manual-reset
LOR. With Sl closed (simulating the commanded or fault
condition) B-A contact closes and E-F contact closes. In this
manner E-F and A-B are both connected to the (+) bus so the
K1 coil sees no voltage difference and cannot operate.
Therefore, the LOR/SR will not reset and may remain in the
TRIP position indefinitely while the RlR2 bridge draws only
enough milliamps to maintain the voltage balance of the bridge
and well below the dropout current of any 0.2 amp. target
relays that may be part of the circuit.
When Sl opens (indicating the fault or pre-determined
condition has cleared), the RlR2 bridge becomes unbalanced
since the E-F contact, although closed, is in the Sl contact
circuit. Kl operates, closing contact Kl and K2 operates, closing
contact K2 and the rotary solenoid LOR/R operates and indexes
to the RESET position completing the cycle.
Contacts E-F and A-B then open, dropping out relays K1
and K2 (and their contacts). Contact F-G closes, setting up the
LOR/SR for the next command.
The TIME DELAY SELF-RESET (shown in RESET
position) version of the LOR/SR, illustrated in Fig. 6,
operates in the same manner as the instantaneous reset version
except the R3-Cl-C2-C3-C4 circuit causes a time delay of
from 300 to 600 milliseconds from the time Sl opens until the
LOR/SR contacts reclose.
*From ANSI/IEEE C 37.90- 1989
The trip and reset solenoid coils provide reliable operation over
a wide RANGE of operating conditions. Trip coils A, B, C, D,
E, and F have substantial overlapping voltage ranges enabling
some "custom-fitting" depending on the desired speed versus
current burden. Trip coils G and H have controlled threshold
voltage levels to insure that the unit will not trip at half-voltage.
G and H coils are useful where cummulative stray voltages due
to capacitive and other effects might be impressed on the LOR
coil causing occasional nuisance trips. The full voltage ranges
are shown on Tables II and III.
The Threshold Voltage shown is the minimum level that
can produce a TRIP operation. This is not a reliable operation
and this voltage level should not be normally used. The normal
operation should be within the limits of the Operating Range.
The Operating Range represents the design limits for
reliable operation. Safety factors are included so operation can
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occur above and below the indicated range as previously
explained.
TABLE II
Trip Coil Voltage Data
COIL
TABLE IV
Coil Burden Data
TRIP COIL
COIL
BURDEN
CIRCUIT
(amps)
DC
@ RATED
OHMS
VOLTAGE
@ 25
o
C
3.3
7.7
13.0
27.0
50.0
104.0
27.0
104.0
27.0
7.3
3.1
3.7
4.6
2.5
2.4
4.6
2.4
4.6
RESET COIL
COIL
CIRCUIT
DC OHMS
@ 25
o
C
0.7
--
3.0
12.4
--
80.6
--
--
--
BURDEN
(amps)
@ RATED
VOLTAGE
33.8
--
15.9
10.1
--
3.1
--
--
--
COIL
CIRCUIT
VOLTS
COIL
A
B
C
D
E
F
G
H
K
NOMINAL
VOLTAGE
24 VDC
24 VDC
48 VDC
125VDC
120 VAC
125 VDC
250 VDC
240 VAC
125 VDC
250 VDC
125 VDC
THRESHOLD
VOLTAGE
6 VDC
9 VDC
12 VDC
16 VDC
20 VAC
23 VDC
33 VDC
40 VAC
70 VDC
140 VDC
16 VDC
OPERATING
RANGE
10 - 40 VDC
18 - 50 VDC
24 - 70 VDC
30 - 140 VDC
30 - 140 VAC
45 - 140 VDC
70 - 280 VDC
60 - 280 VAC
90 - 140 VDC
180 - 280 VDC
100 - 150 VDC
A
B
C
D
E
F
G
H
K
24 VDC
24 VDC
48 VDC
125 VDC
125 VDC
250 VDC
125 VDC
250 VDC
125 VDC
Trip Coil Current - Voltage Characteristics
The trip coils may be used over a wide range of voltage
levels as previously described. To aid in this selection Fig. 7
graphs the voltage/current characteristics of the trip coils. These
values are the same for the manual-reset LOR, the electric-reset
LOR/ER, and the self-reset LOR/SR Lock-out Relays. Fig. 7 is
used with the Response Time graph of Fig. 8. Target selection
data is detailed on Table V and VI and Fig. 9 to 12.
Note: D coil has been tested and approved for use @ 120VAC
TABLE III
Reset Coil Voltage Data
COIL
A
C
D
F
NOMINAL
VOLTAGE
24 VDC
48 VDC
125 VDC
250 VDC
OPERATING
RANGE
19.2 to 28 VDC
38.4 to 57.6 VDC
100 to 140 VDC
200 to 275 VDC
Coil Burden Data
The LOR, LOR/ER, and LOR/SR solenoid coil burden
data is outlined in Table IV.
As previously explained, the control bus needs to be able to
supply the burden detailed in Table IV but does not need to
interrupt it – the units are self-interrupting. The reset coil is
hard-wired to the control bus so the actuating means (S2 in Fig.
4) is not subjected to the burden (only the K1 coil burden at
less than 1 ampere) S1 controlling the trip coil does “make”
and carry the trip coil current.
Fig. 7. Trip Solenoid Coil Burden Data
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