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STUDY IN ELECTROMECHANICAL
RELAYS RELIABILITY
Javier Pablos Abelairas
CERN TE-MPE-TM
3rd OCTOBER 2013
Outline
CERN
Introduction to relays
Scope of the study
The test bench
Results
Conclusions
[11]
TE-MPE-TM 3rd OCTOBER 2013
2
Outline
CERN
Introduction to relays
Scope of the study
The test bench
Results
Conclusions
[11]
TE-MPE-TM 3rd OCTOBER 2013
3
Relay: What is it?
CERN
 It is an electrically operated switch that opens or closes a circuit.
 A very useful electrical component :
• to control a high-power circuit by a low-power signal.
• In circuits where several circuits must be controlled by one signal.
 Complete electrical isolation between control and controlled circuit
 Widely used electronic component in safety systems. Protective relays
can prevent equipment damage by detecting electrical abnormalities,
including overcurrent, undercurrent, overloads and reverse currents.
 At CERN there are more than 64000 protective relays in the machine
TE-MPE-TM 3rd OCTOBER 2013
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Relay: History
CERN
 Invented in 1835 by the American scientist Joseph Henry.
 Developed to improve his version of the electrical telegraph,
developed earlier in 1831.
 Relays were also used as a constructive part of some early
calculators and computers.
 Samuel Morse used Henry's relay device to carry morsecode signals over long kilometres of wire.
 In 1878 the American company Western-Electric used
electric relays designed by Edison in telephone systems.
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Relays: Applications
CERN
 Widely used electronic component in applications within different fields:
•
Telecommunications:
− Antenna switches for UMTS
− GSM base stations
− Radio base Stations
•
Data communications:
− Embedded modem data access arrangement
− PC modem discrete DAA circuits
− Radio base Stations
•
Industrial:
− Industrial control systems
− Remote monitoring
− Ground isolation
− Speed controls
•
Security Systems:
− Alarm switches
− Sensor switches
− Safety Gate
TE-MPE-TM 3rd OCTOBER 2013
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Relays: Manufacturers
CERN
TE-MPE-TM 3rd OCTOBER 2013
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Relays: Classification
CERN
Control Safety Relay
With a contact
Mechanical Relay
Without a contact
Hybrid
Semi-Conductor Relay
Mechanical and semi-conductor
Relay
(SSR (Solid State Relays))
The contact opens and shuts mechanically
The output part is a semi-conductor
and does not open and shut mechanically.
TE-MPE-TM 3rd OCTOBER 2013
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Relays: SSR vs EMR
CERN
Solid State Relay (SSR): electronic switching device in which the load current is
conducted by semiconductors instead of mechanical contacts. The output
semiconductor device (SCR, TRIAC, or transistor) is optically-coupled to a LED
light source inside the relay.
Electromechanical Relay (EMR): electrically operated switches that complete or
interrupt a circuit by physically moving contacts mechanically.
TE-MPE-TM 3rd OCTOBER 2013
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Relays: SSR vs EMR
CERN
ADVANTAGES
Solid State Relay SSR
Electromechanical Relay EMR
- Smaller size
- Cheaper
- Long operation life
- Input and output circuit are electrically isolated
- Low switching time (fast)
- Lower contact resistance
- Quiet operation (no acoustic noise)
- Lower contact capacitance (good for HF circuits)
- Electromagnetic noise resistance and low electrical
interference generation.
- No heat sink required
- No contact arcing or bouncing.
- Tend to fail in an open state
- ‘Zero-cross’ circuitry for AC loads
- Single input / multiple output capability. Control of
several circuits
- No moving parts to wear out which means it is shock
and vibration resistant, improving system reliability.
- Consume less power
- Low input power consumption reducing heat
dissipation requirements .
TE-MPE-TM 3rd OCTOBER 2013
- High resistance to EMI and overvoltages
- Available in extremely high voltage and current
ratings
10
Relays: SSR vs EMR
CERN
ADVANTAGES
Solid State Relay SSR
Electromechanical Relay EMR
- Smaller size
- Cheaper
- Long operation life
- Input and output circuit are electrically isolated
- Low switching time (fast)
- Lower contact resistance
- Quiet Operation (no acoustic noise)
- Lower contact capacitance (good for HF circuits)
- Electromagnetic noise resistance and low electrical
interference generation.
- No heat sink required
- No contact arcing or bouncing.
- Tend to fail in an open state
- ‘Zero-cross’ circuitry for AC loads
- Single input / multiple output capability. Control of
several circuits
- No moving parts to wear out meaning shock and
vibration resistant, improving system reliability.
- Consume less power
- Low input power consumption reducing heat
dissipation requirements .
TE-MPE-TM 3rd OCTOBER 2013
- High resistance to EMI and overvoltages
- Available in extremely high voltage and current
ratings
11
Relays: EMR
CERN
Principle of operation:
•
When energized an electric current passes through the coil generating
a magnetic field.
•
The magnetic field activates the armature towards the iron yoke.
•
The armature produces the movement of the contact that either
makes or breaks a connection with a fixed contact
•
When de-energized the armature is placed back into its initial position
by a spring or by gravity
TE-MPE-TM 3rd OCTOBER 2013
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Relays: Safety Relays
CERN
•
Type of relay with forcibly guided contacts,
i.e., contacts that are mechanically linked
together.
•
Impossible that NO (normally open) and
NC (normally closed) contacts could be
closed at the same time.
•
Used in applications where safety is a
requirement.
•
Ensure the safety function even if contacts
are welded together.
•
Requirement of EN 50205 Standard
•
So called Class A Safety Relays
•
Mark
on the nameplate
TE-MPE-TM 3rd OCTOBER 2013
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Relays: Parameters
CERN
Ambient Operating Temperature: Temperature measured directly in the vicinity of the
relay. The maximum allowed value may not be exceeded, otherwise there is a chance
for relay failure. Ambient temperature range according to IEC 61810-1
Maximum Switching frequency: Maximum switching frequency which satisfies
the mechanical or electrical life under repeated operations by applying a pulse train at
the rated voltage to the operating coil.
Electronic symbol:
COIL SPECIFICATIONS:
•
Coil Current: Current drawn by the coil for generating the magnetic pull force. At the moment of
switching the coil on, the current is higher than in continuous use.
•
Coil Resistance: Electrical resistance of the coil at reference temperature. It varies with
temperature.
•
Nominal Coil Operate Voltage: The voltage required in order to make the relay operate.
•
Dropout / release voltage: Voltage applied to the coil below which all the contacts of an
operating relay must revert to non-operating position.
TE-MPE-TM 3rd OCTOBER 2013
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Relays: Parameters
CERN
Mechanical Endurance (Mechanical Life): Number of switching operations without
contact load during which the relay remains within the specified characteristics.
Electrical Endurance (Electrical Life): Number of switching operations until failure of a
relay under defined conditions of load and of ambient influences. The reference value
specified for the endurance applies to a resistive load. At lower contact loads a
substantially longer electrical life is achieved.
CONTACT SPECIFICATIONS:
•
Number of contacts
•
Contact Resistance: Electrical resistance between the relay terminals of a closed contact circuit,
measured with nominal current and voltage.
•
Maximum Carrying Current: Maximum current which, after closing or prior to opening, the
contacts can safely pass without being subject to temperature rise in excess of their design limit.
•
Maximum Switching Current: Maximum current that can safely be switched by the contacts.
TE-MPE-TM 3rd OCTOBER 2013
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Relays: Parameters
CERN
Contact forms: Different types of contact arrangements
Form Description
Short
Description
NARM designator
Make Contact
Form A
NO
SPST-NO
Break Contact
Form B
NC
SPST-NC
Changeover Contact
Form C
CO
SPDT
Double make on armature
Form U
SPST-NO DM
Double brake on armature
Form V
SPST-NC DB
Double make contact
Form X
SPST-NO DM
Double brake contact
Form Y
SPST-NC DB
Double brake, Double make contact
Form Z
SPDT-NC-NO DBDM
Triple make contact
Form 3
TE-MPE-TM 3rd OCTOBER 2013
Circuit Symbol
16
Relays: Parameters
CERN
Contact material: Major influence on the performance of a relay affecting maximum
inrush current, maximum switching current, contact resistance, etc. together with
contact reliability and electrical life.
Good electrical and thermal conductivity. Exhibits low contact resistance, but low r esistance against aggressive atmosphere. Easily
Fine Grain Silver
develops a sulphide film in a sulphide atmosphere. The addition of 0.15% Ni gives the alloy a greater mechanical stability reducing welding
AgNi 0.15
and contact wear. Universally applicable in medium and low load range, especially in DC circuits, ≥ 12V, 10 mA
Silver-Nickel
AgNi10
Contact
Material
Surface
Finish
Used for switching loads in the rage of >100mA. High resistance to contact wear and low welding tendency. Slightly higher contact
resistance than AgNi0.15. Mainly used in DC switching particularly in automotive applications where high inrush current occur e.g. when
switching lamps.
Silver-Cadmium- Very high resistance to contact wear and welding. Good thermal and mechanical stability. Particularly suited for switching inductive or high
oxide
current loads like motors, heating resistors, solenoids etc. High contact resistance and sulphide films form easily.
AgCdO
Silver-Tin-Oxide
AgSnO2
Higher melting point and higher thermal stability than AgCdO and therefore greater resistance to welding. Also contact erosion rate is
lower because any arc spreads to the outside of the contact preventing creation of a local hot spot and potential weld. High contact life,
minimum material migration. It is mainly used for circuits with high requirements to make and break currents, DC and AC coils, like
fluorescent light loads.
Palladium Copper
PdCu
Greater hardness, low contact wear and stable contact resistance. Good corrosion and sulphidation resistance. Very low material migration
compared to other contact materials. Expensive. Mainly used for Flasher applications in Automobiles.
Tungsten
W
Highest melting point, high wear resistance with heavy loads, little transfer of material, best suited for breaking heavy inductive
loads. Not recommended. Used as pre-contact in circuits with highest make and break loads ≥ 60V, 1A
Rh plating
(rhodium)
Combines perfect corrosion resistance and hardness. As plated contacts, used for relatively light loads. In an organic gas atmosphere, care
is required as polymers may develop. Therefore, it is used in hermetic sealed relays (reed relays, etc.). Expensive.
Au clad
(gold clad)
Gold with its excellent corrosion resistance is pressure welded onto a base metal. Special characteristics are uniform thickness and the
nonexistence of pinholes. Greatly effective especially for low level loads under relatively adverse atmospheres.
Tungsten
W
The purpose is to protect the contact base metal during storage of the switch or device with built-in switch. However, a certain degree of
contact stability can be obtained even when switching loads.
TE-MPE-TM 3rd OCTOBER 2013
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Relays: Parameters
CERN
Contact material: Major influence on the performance of a relay affecting maximum
inrush current, maximum switching current, contact resistance, etc. together with
contact reliability and electrical life.
Good electrical and thermal conductivity. Exhibits low contact resistance, but low r esistance against aggressive atmosphere. Easily
Fine Grain Silver
develops a sulphide film in a sulphide atmosphere. The addition of 0.15% Ni gives the alloy a greater mechanical stability reducing welding
AgNi 0.15
and contact wear. Universally applicable in medium and low load range, especially in DC circuits, ≥ 12V, 10 mA
Silver-Nickel
AgNi10
Contact
Material
Surface
Finish
Used for switching loads in the rage of >100mA. High resistance to contact wear and low welding tendency. Slightly higher contact
resistance than AgNi0.15. Mainly used in DC switching particularly in automotive applications where high inrush current occur e.g. when
switching lamps.
Silver-Cadmium- Very high resistance to contact wear and welding. Good thermal and mechanical stability. Particularly suited for switching inductive or high
oxide
current loads like motors, heating resistors, solenoids etc. High contact resistance and sulphide films form easily.
AgCdO
Silver-Tin-Oxide
AgSnO2
Higher melting point and higher thermal stability than AgCdO and therefore greater resistance to welding. Also contact erosion rate is
lower because any arc spreads to the outside of the contact preventing creation of a local hot spot and potential weld. High contact life,
minimum material migration. It is mainly used for circuits with high requirements to make and break currents, DC and AC coils, like
fluorescent light loads.
Palladium Copper
PdCu
Greater hardness, low contact wear and stable contact resistance. Good corrosion and sulphidation resistance. Very low material migration
compared to other contact materials. Expensive. Mainly used for Flasher applications in Automobiles.
Tungsten
W
Highest melting point, high wear resistance with heavy loads, little transfer of material, best suited for breaking heavy inductive
loads. Not recommended. Used as pre-contact in circuits with highest make and break loads ≥ 60V, 1A
Rh plating
(rhodium)
Combines perfect corrosion resistance and hardness. As plated contacts, used for relatively light loads. In an organic gas atmosphere, care
is required as polymers may develop. Therefore, it is used in hermetic sealed relays (reed relays, etc.). Expensive.
Au clad
(gold clad)
Gold with its excellent corrosion resistance is pressure welded onto a base metal. Special characteristics are uniform thickness and the
nonexistence of pinholes. Greatly effective especially for low level loads under relatively adverse atmospheres.
Tungsten
W
The purpose is to protect the contact base metal during storage of the switch or device with built-in switch. However, a certain degree of
contact stability can be obtained even when switching loads.
TE-MPE-TM 3rd OCTOBER 2013
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Relays: Parameters
CERN
Relay Cycles (dynamic response): Due to the self-induction of the coil and the inertia of
the parts to be moved, on activating a relay the operations do not take place suddenly:
Operate time: Time from the initial application of power to the coil until the closure of the
normally open contacts (excluding bounce time).
•
Bounce Time: Time interval between the first and final closing of a contact, caused
by a mechanical shock process in contact movement (contact bounce)
•
Release Time / Reset Time: The time from the initial removal of power from the coil until
the re-closure of the normally closed contacts. Excluding bounce time.
•
Transit time / Transfer Time: The movement time of the armature after opening of the
one contact set (e.g. NC) before closing of the other (e.g. NO).
Coil supply
•
Contact current
1
t
Operate Time
NO Contact
0
1
0
t
Release Time
Transit Time
NC Contact
Bounce Time
t
1
0
CO Contact
t
1
TE-MPE-TM 3rd OCTOBER 2013
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Relays: Failures
CERN
Relays can fail for a variety of reasons: accidents,
manufacturing defects or simply because they have
reached the end of their life.
Failure Mode
Relative Probability
Failure to trip
55%
Spurious trip
26%
Short
19%
Most common failure mechanism:
•
Contamination of contacts with oxides or deposits:
− Metallic: causes short conditions due to contact welding.
− Non-metallic (gas): causes open circuits when material is periodically deposited.
•
Mechanical wear of internal switching elements (contact migration, contact pitting)
•
Other: Open and shorted coils, loose resiliency of the spring.
Failures in the system due to safety relays: contact bounce, arcing interference with nearby
electrical instruments and sensors…
TE-MPE-TM 3rd OCTOBER 2013
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Outline
CERN
Introduction to relays
Scope of the study
The test bench
Results
Conclusions
[11]
TE-MPE-TM 3rd OCTOBER 2013
21
Scope
CERN
 Design of a remote power cycle option for the upgraded protection units DQLPU and
DQGPU type B.
DQLPU (Local Protection Units): Integrate the
protection electronics and DAQ systems for the
LHC main magnet protection.
•
•
DQLPU
DQLPU type A: MB protection, 1232 units.
DQLPU type B: MQ protection, 392 units.
DQGPU
DQGPU type B (Global Protection Units): In
charge of the protection of the Individually
Powered Dipole (IPD) and the Individually
Powered Quadrupole (IPQ).
 Future upgrades of the beam interlock system or any other protection system since they
are intended to reliably monitor the signals from safety devices and switch off quickly in
an emergency.
TE-MPE-TM 3rd OCTOBER 2013
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Relays in QPS
CERN
Crate
Description
Power cycle
Interlock
DQHDS trigger
DQLPU type A
MB protection
Relay
Relay
Relay
DQLPU type B
MQ protection
Not yet implemented
Relay
Relay
DQLPU type S
Symmetric quench
and bus-bars
Relay
Relay /
PhotoMOS
Relay
DQGPU type A
Corrector magnets Relay (external)
PhotoMOS
N/A
DQGPU type B
Insertion region
magnets (IPD,
IPQ)
Not implemented
PhotoMOS
PhotoMOS
DQGPU type C
Inner triplets
Not implemented
PhotoMOS
PhotoMOS
DQGPU type D
HTS current leads
Relay (external)
PhotoMOS
N/A
TE-MPE-TM 3rd OCTOBER 2013
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Outline
CERN
Introduction to relays
Scope of the study
The test bench
Results
Conclusions
[11]
TE-MPE-TM 3rd OCTOBER 2013
24
Test Bench Setup
CERN
•
Parameter under study: mechanical endurance, contact bouncing, operate time and
release time.
•
3 sets of relays depending on whether they have 5V, 12V or 24V nominal coil voltage.
•
Relays with different contact configuration 1, 2, 4, 6, 8 poles.
NI PCI-6014
Acquisition Board
16 analog Input
(8 differential)
2 analog output
8 digital I / O
NI CB-68LP
Connector Block
Relay Board
5V
TE-MPE-TM 3rd OCTOBER 2013
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Test Bench Setup
CERN
•
Same control signal energizes all the relays so it is possible to compare different
response times between relays
•
One output signal per relay
•
Schema of the electronic control circuit of a single relay of 2 poles
Logic circuit gathers all the signals from the contacts.
TE-MPE-TM 3rd OCTOBER 2013
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Test Bench Setup: 5V Relays
CERN
Relay 11
PANASONIC
Relay 12
FINDER
Relay 13
SCHRACK
Relay 14
SCHRACK
1 CO
1 NO
1 CO
1 NO
AgSnO2
AgCdO
AgSnO2
AgSnO2, gold plated
5V
5V
5V
5V
Minimum Operating Voltage
3.5V
3.9V
3.5V
5V
Release Voltage
0.5V
0.5V
0.25V
0.25V
Coil Resistance
69.4 ± 10% Ω
125
147 ± 10% Ω
147 ± 10% Ω
Dimensions L x W x H (mm)
22x16x19.9
20x10x10.7
28x5x18.5
28x5x18.5
Ambient Operating
Temperature
(-40) to 85oC
(-40) to 85oC
(-40) to 85oC
(-40) to 85oC
12
6.4
6
6
Mechanical Endurance
107 operations
107 operations
107 operations
107 operations
Max. Switching Current
5A
6A
6A
6A
Operate / Release Time
10 / 10 ms
6 / 2 ms
12 / 5 ms
5 / 2.5 ms
Brand
Image
Number of contacts
Contact Material
Rated Voltage
Weight (g)
TE-MPE-TM 3rd OCTOBER 2013
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Test Bench Setup: 12V Relays
CERN
Relay 5
Relay 6
Relay 7
Relay 8
Relay 9
Relay 10
ELESTA RELAYS
FINDER
DOLD
PANASONIC
SCHRACK
FINDER
Number of contacts
4 (3NO + 1NC)
2 CO
6 (3NO + 3NC)
8 (4NO + 4NC)
6 (3NO + 3NC)
1 CO
Contact Material
AgSnO2 + 0.2μm
Au
AgSnO2
AgNi10 + 0.2μm
Au
Au-flashed AgSnO2
AgSnO2 + 0.2μm
Au
AgSnO2
Rated Voltage
12V
12V
12V
12V
12V
12V
Minimum Operating
Voltage
9V
9V
8.4V
9V
9V
9V
Release Voltage
1.2V
1.2V
1.2V
1.8V
1.2V
1.2V
Coil Resistance
140 ± 10% Ω
205 Ω
180 ± 10% Ω
288 ± 10% Ω
180 ± 10% Ω
400 Ω
Dimensions L x W x H (mm)
36.1x12.5x29.1
29x12.4x30
41.5x14.5x33.2
53.3x33x19
55x16.5x19.8
19x15.5x20
Ambient Operating
Temperature
(-40) to 70oC
(-40) to 70oC
(-40) to 85oC
(-40) to 70oC
(-25) to 70oC
(-40) to 85oC
Weight (g)
25
20
38
47
30
10
Mechanical Endurance
107 operations
107 operations
5 x 107 operations
107 operations
107 operations
107 operations
Max. Switching Current
8A
8A
8A
6A
8A
10A
Operate / Release Time
8 / 4 ms
10 / 4 ms
20 / 6 ms
30 / 15 ms
11 / 3 ms
9 / 3 ms
Brand
Image
TE-MPE-TM 3rd OCTOBER 2013
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Test Bench Setup: 24V Relays
CERN
Relay 1
Relay 2
Relay 3
Relay 4
SCHRACK
HENGSTLER
OMROM
HENGSTLER
Number of contacts
4 (3NO + 1NC)
4 (2NO + 2NC)
6 (3NO + 3NC)
6 (4NO + 2NC)
Contact Material
AgSnO2
AgNi + 0.2μm Au
Rated Voltage
24V
24V
24V
24V
Minimum Operating Voltage
18V
18.1V
18V
15.5V
Release Voltage
2.4V
4.3V
2.4V
3V
Coil Resistance
720 ± 10 Ω
1020 ± 8 Ω
1152
480 ± 8 Ω
Dimensions L x W x H (mm)
40x13x19.5
44.6x12.5x30
40x13x27.5
57.8x20.5x48.6
Ambient Operating
Temperature
(-25) to 70oC
(-25) to 80oC
(-20) to 70oC
(-25) to 80oC
Weight (g)
30
31
25
115
Mechanical Endurance
107 operations
107 operations
107 operations
107 operations
Max. Switching Current
8A
8A
6A
10A
Operate / Release Time
12 / 20 ms
15 / 8 ms
20 / 20 ms
17 / 7 ms
Brand
Image
TE-MPE-TM 3rd OCTOBER 2013
AgCdO
29
CERN
Test Bench Setup: Power Supply
12V
24V
TE-MPE-TM 3rd OCTOBER 2013
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Test Bench Setup
CERN
TE-MPE-TM 3rd OCTOBER 2013
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Tests
CERN
Three different tests were executed:
1. Operate the relays to
occurs




their mechanical endurance to observe whether breakdown
Test duration: 24 days/lot
Operation frequency: 5 Hz
Resolution: 1ms
Number of cycles ≈ 10x106
2. Operate the relays once every 15 days to simulate a power cycle scenario.
 Test duration: 6 months
 Number of operations = 12
3. The relays were energized for 1 day (voltage applied to the coil) and afterwards
operated normally for 1 day
 Test duration: 14 days
 Operation frequency: 1 Hz
 Number of operations ≈ 86000/day
TE-MPE-TM 3rd OCTOBER 2013
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Outline
CERN
Introduction to relays
Scope of the study
The test bench
Results
Conclusions
[11]
TE-MPE-TM 3rd OCTOBER 2013
33
CERN
Results: Relay Reliability
Reliability: Ability of a system or component to fulfil a certain function under stated conditions
for a specified period of time.
Relays do not age until switched. Reliability may be expressed as the number of switch cycles
before wear-out rather than the more traditional failure rates (MTBF/MTTF).
TE-MPE-TM 3rd OCTOBER 2013
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Results: Test 1
CERN
TEST 1
[11]
TE-MPE-TM 3rd OCTOBER 2013
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CERN
Results: Response Times Test 1
Operate Time
∙∙∙∙∙∙∙∙∙ Release Time-
TE-MPE-TM 3rd OCTOBER 2013
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Results: Response Times Test 1
CERN
•
No relay breakdowns after 10x106 operations.
•
There is a mild rising trend in the response time of the relay over time.
•
Most of the relays didn’t meet the datasheet specifications provided by manufacturers.
Relay
Voltage
Contacts
Operate Time (Mean/ SD / Datasheet)
Relase Time (Mean / SD / Datasheet)
PANASONIC
5V
1 (CO)
5.55ms / 0.07ms / 10ms
7ms / 0.15ms / 10ms
FINDER
5V
1 (NO)
5.44ms / 0.1ms / 6ms
7.97ms / 0.19ms / 2ms
SCHRACK
5V
1 (CO)
4.61ms / 0.1ms / 12ms
5.2ms / 0.22ms / 5ms
SCHRACK
5V
1 (NO)
5.58ms / 0.11ms / 5ms
4.78ms / 0.09ms / 2.5ms
ELESTA RELAYS
12V
4 (3NO/1NC)
9.41ms / 0.15ms / 8ms
7.6ms / 0.1ms / 4ms
FINDER
12V
2 (CO)
11.25ms / 0.48ms / 10ms
9.11ms / 0.3ms / 4ms
DOLD
12V
6 (3NO/3NC)
16.87ms / 0.67ms / 20ms
11.43ms / 0.32ms / 6ms
PANASONIC
12V
8 (4NO/4NC)
14.87ms / 0.79ms / 30ms
15.59ms / 0.31ms / 15ms
SCHRACK
12V
6 (3NO/3NC)
15.66ms / 0.86ms / 11ms
6.99ms / 0.34ms / 3ms
FINDER
12V
1 (CO)
14.75ms / 0.6ms / 9m
12.69ms / 0.36ms / 3ms
SCHRACK
24V
4 (3NO/1NC)
9.72ms / 0.45ms / 20ms
11.5ms / 0.33ms / 12ms
HENGSTLER
24V
4 (2NO/1NC)
14.4ms / 0.33ms / 15ms
12.18ms / 0.40ms / 8ms
OMROM
24V
6 (3NO/3NC)
12.01ms / 0.65ms / 20ms
8 ms / 0.23ms / 20ms
HENGSTLER
24V
6 (4NO/2NC)
21.78ms / 0.45ms / 17ms
18.94ms / 0.46ms / 7ms
TE-MPE-TM 3rd OCTOBER 2013
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Results: Contact Bouncing Test 1
CERN
Contact bounce or chatter is a common problem with mechanical components since
they are made of metals which exhibit spring-like behaviour. The use of ‘de-bouncing’
circuits eradicates this undesirable behaviour.
Relay1
Voltage
Contacts
Operate time
Bounces
Percentage (over 10x106)
PANASONIC
5V
1 (CO)
5.55ms
0
0
FINDER
5V
1 (NO)
5.44ms
0
0
SCHRACK
5V
1 (CO)
4.61ms
0
0
SCHRACK
5V
1 (NO)
5.58ms
0
0
ELESTA RELAYS
12V
4 (3NO/1NC)
9.41ms
13
≈0
FINDER
12V
2 (CO)
11.25ms
47
≈0
DOLD
12V
6 (3NO/3NC)
16.87ms
114356
1.14
PANASONIC
12V
8 (4NO/4NC)
14.87ms
45365
0.45
SCHRACK
12V
6 (3NO/3NC)
15.66ms
0
0
FINDER
12V
1 (CO)
14.75ms
456
0.004
SCHRACK
24V
4 (3NO/1NC)
9.72ms
0
0
HENGSTLER
24V
4 (2NO/1NC)
14.4ms
23
≈0
OMROM
24V
6 (3NO/3NC)
12.01ms
34678
0.34
HENGSTLER
24V
6 (4NO/2NC)
21.78ms
69841
0.69
TE-MPE-TM 3rd OCTOBER 2013
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Results: Test 2
CERN
TEST 2
[11]
TE-MPE-TM 3rd OCTOBER 2013
39
CERN
Results: Response Times Test 2
Operate Time
∙∙∙∙∙∙∙∙∙ Release Time-
TE-MPE-TM 3rd OCTOBER 2013
40
Results: Response Times Test 2
CERN
The results show that after a period of time without being active, the operate time
of the relay is slightly longer while the release time keeps mostly the same.
Relay1
Voltage
Contacts
Operate Time (Mean / Mean Test 1)
Relase Time (Mean / Mean Test 1)
PANASONIC
5V
1 (CO)
5.7ms / 5.55ms
6.89ms / 7ms
FINDER
5V
1 (NO)
5.57ms / 5.44ms
7.82ms / 7.97ms
SCHRACK
5V
1 (CO)
4.77ms / 4.61ms
5.15ms / 5.2ms
SCHRACK
5V
1 (NO)
5.56ms / 5.58ms
4.74ms / 4.78ms
ELESTA RELAYS
12V
4 (3NO/1NC)
9.54ms / 9.41ms
7.61 ms / 7.6ms
FINDER
12V
2 (CO)
11.63ms / 11.25ms
9.17 ms / 9.11ms
DOLD
12V
6 (3NO/3NC)
17.32ms / 16.87ms
11.45 ms / 11.43ms
PANASONIC
12V
8 (4NO/4NC)
15.07ms / 14.87ms
15.51ms / 15.59ms
SCHRACK
12V
6 (3NO/3NC)
16.51ms / 15.66ms
7.01ms / 6.99ms
FINDER
12V
1 (CO)
14.72ms / 14.75ms
12.68ms / 12.69ms
SCHRACK
24V
4 (3NO/1NC)
10.25 ms / 9.72ms
11.56ms / 11.5ms
HENGSTLER
24V
4 (2NO/1NC)
14.58ms / 14.4ms
12.26ms / 12.18ms
OMROM
24V
6 (3NO/3NC)
12.69ms / 12.01ms
7.93 ms / 8ms
HENGSTLER
24V
6 (4NO/2NC)
21.91ms / 21.78ms
18.64ms / 18.94ms
TE-MPE-TM 3rd OCTOBER 2013
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Results: Test 3
CERN
TEST 3
[11]
TE-MPE-TM 3rd OCTOBER 2013
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CERN
Results: Response Times Test 3
Operate Time
∙∙∙∙∙∙∙∙∙ Release Time-
TE-MPE-TM 3rd OCTOBER 2013
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Results: Response Times Test 3
CERN
Following a day left in an energized state, the first release time of each relay was longer
than the rest.
Relay1
Voltage
Contacts
First Release
Time
Operate Time (Mean / Mean Test 1)
Release Time (Mean / Mean Test 1)
PANASONIC
5V
1 (CO)
7.54ms
5.61ms / 5.55ms
7.06ms / 7ms
FINDER
5V
1 (NO)
8.96ms
5.46ms / 5.44ms
7.97ms / 7.97ms
SCHRACK
5V
1 (CO)
5.55ms
4.64ms / 4.61ms
5.22ms / 5.2ms
SCHRACK
5V
1 (NO)
5.19ms
5.55ms / 5.58ms
4.82ms / 4.78ms
ELESTA RELAYS
12V
4 (3NO/1NC)
7.99ms
9.43ms / 9.41ms
7.66 ms / 7.6ms
FINDER
12V
2 (CO)
9.58ms
11.29ms / 11.25ms
9.17 ms / 9.11ms
DOLD
12V
6 (3NO/3NC)
12.02ms
16.84ms / 16.87ms
11.52 ms / 11.43ms
PANASONIC
12V
8 (4NO/4NC)
15.83ms
14.97ms / 14.87ms
15.56ms / 15.59ms
SCHRACK
12V
6 (3NO/3NC)
7.72ms
15.60ms / 15.66ms
7.23ms / 6.99ms
FINDER
12V
1 (CO)
12.91ms
14.80ms / 14.75ms
12.63ms / 12.69ms
SCHRACK
24V
4 (3NO/1NC)
11.95ms
10. 07 ms / 9.72ms
11.69ms / 11.5ms
HENGSTLER
24V
4 (2NO/1NC)
12.78ms
14.4ms / 14.4ms
12.23ms / 12.18ms
OMROM
24V
6 (3NO/3NC)
8.44ms
12.23ms / 12.01ms
7.93 ms / 8ms
HENGSTLER
24V
6 (4NO/2NC)
19.54ms
21.80ms / 21.78ms
18.76ms / 18.94ms
TE-MPE-TM 3rd OCTOBER 2013
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Outline
CERN
Introduction to relays
Scope of the study
The test bench
Results
Conclusions
[11]
TE-MPE-TM 3rd OCTOBER 2013
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Conclusions
CERN
 The most important factor affecting relay reliability is the system in which the relay will be
placed. The selection of the right dimensions, contact material, number of poles,
switching capacity for inrush currents and other features is crucial for its performance and
reliability.
 The most common relay failure is: failure to trip which should be taken into account when
defining the safety system.
 There is a direct relation between the length of the contacts and the time response of the
relay. Bouncing is more notable in relays with longer contacts. Relays from SCHRACK
manufacturer had an excellent behaviour in terms of time response and bouncing. DOLD
and PANASONIC safety relays showed the worst performance.
 The more contacts driven by the armature, the higher response time.
 No relay breakdown occurred even after exceeding the mechanical endurance
specification.
 Relay dynamic response worsens with the number of operations.
 After a period of inactivity, the operate time is slightly longer. After being energized for a
long period of time, the release time is longer.
TE-MPE-TM 3rd OCTOBER 2013
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End
CERN
THANKS FOR YOUR ATTENTION
[11]
TE-MPE-TM 3rd OCTOBER 2013
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