Proax
Currency
0 Items
Products
Manufacturers
Expertise
About UsBlogQuick OrderContact UsClearance
proax logo
Cart
Phoenix Contact 2904611
AllPower ProductsPower supply
Phoenix ContactOfficial Distributor

By Phoenix Contact

SKU
MPN
QUINT4-PS/1AC/48DC/10
Weight
1.64 kg
This product is Not Cancellable/Not Returnable
Series QUINT4-PS

QUINT4-PS/1AC/48DC/10 - Power supply unit

Primary-switched QUINT POWER power supply for DIN rail mounting with free choice of output characteristic curve and SFB (Selective Fuse Breaking) technology, input: 1-phase, output: 48 V DC / 10 A

  • Preventive function monitoring indicates critical operating states before errors occur
  • Signaling thresholds and characteristic curves that can be adjusted via NFC maximize system availability
  • Power reserve for easy system extension thanks to static boost with sustained power of up to 125% and ability to start difficult loads thanks to dynamic boost with up to 200% for 5 seconds
  • High degree of immunity, thanks to integrated gas-filled surge arrester and mains failure bridging time of more than 20 milliseconds
  • Robust design thanks to metal housing and wide temperature range from -40°C to +70°C
  • Worldwide use thanks to the wide range input and international approval package
Technical Specifications

Input data

Control input (configurable) RemOutput power ON/OFF (SLEEP MODE)
DefaultOutput power ON (>40 kΩ/24 V DC/open bridge between Rem and SGnd)

AC operation

Nominal input voltage range100 V AC ... 240 V AC
Input voltage range100 V AC ... 240 V AC -15 % ... +10 %
Derating< 100 V AC (1 %/V)
Electric strength, max.300 V AC 60 s
Typical national grid voltage120 V AC
Typical national grid voltage230 V AC
Voltage type of supply voltageAC
Inrush Currenttyp. 11 A (at 25 °C)
Inrush current integral (I2t)< 0.4 A2s
Inrush current limitation11 A (after 1 ms)
AC frequency range50 Hz ... 60 Hz -10 % ... +10 %
Frequency range (fN)50 Hz ... 60 Hz -10 % ... +10 %
Frequency range (fN)16.7 Hz (acc. to EN 50163)
Mains buffering timetyp. 32 ms (120 V AC)
Mains buffering timetyp. 32 ms (230 V AC)
Current consumption6.8 A (100 V AC)
Current consumption5.5 A (120 V AC)
Current consumption2.8 A (230 V AC)
Current consumption2.7 A (240 V AC)
Nominal Power Consumption519 VA
Protective circuitTransient surge protection; Varistor, gas-filled surge arrester
Switch-on time< 1 s
Typical response time300 ms (from SLEEP MODE)
Input fuse12 A (slow-blow, internal)
Recommended breaker for input protection10 A ... 16 A (Characteristic B, C, D, K or comparable)
Discharge current to PE< 3.5 mA
Discharge current to PE1.3 mA (264 V AC, 60 Hz)

DC operation

Nominal input voltage range110 V DC ... 250 V DC
Input voltage range110 V DC ... 250 V DC -18 % ... +40 %
Derating< 110 V DC (1 %/V)
Voltage type of supply voltageDC
Current consumption6 A (110 V DC)
Current consumption2.5 A (250 V DC)

Output data

Efficiencytyp. 94 % (120 V AC)
Efficiencytyp. 95 % (230 V AC)
Output characteristicU/I Advanced
Output characteristicSmart HICCUP
Output characteristicFUSE MODE
Nominal Output Voltage48 V DC
Setting range of the output voltage (USet)48 V DC ... 56 V DC (constant capacity)
Nominal output current (IN)10 A
Static Boost (IStat.Boost)12.5 A
Dynamic Boost (IDyn.Boost)15 A (5 s)
Selective Fuse Breaking (ISFB)60 A (15 ms)
Magnetic circuit breaker trippingA1...A13 / B2...B6 / C1...C3 / Z1...Z10
Derating> 60 °C ... 70 °C (2.5 %/K)
Feedback voltage resistance≤ 60 V DC
Protection against overvoltage at the output (OVP)≤ 60 V DC
Control deviation< 0.5 % (Static load change 10 % ... 90 %)
Control deviation< 2 % (Dynamic load change 10 % ... 90 %, (10 Hz))
Control deviation< 0.25 % (change in input voltage ±10 %)
Residual ripple< 70 mVPP (with nominal values)
Short-circuit-proofyes
No-load proofyes
Output Power480 W
Output Power600 W
Output Power720 W
Apparent power660 VA (120 V, UOUT = 48 V, IOUT = stat. Boost)
Apparent power644 VA (230 V, UOUT = 48 V, IOUT = stat. Boost)
Maximum no-load power dissipation< 5 W (120 V AC)
Maximum no-load power dissipation< 5 W (230 V AC)
Power loss nominal load max.< 36 W (120 V AC)
Power loss nominal load max.< 28 W (230 V AC)
Power dissipation SLEEP MODE< 5 W (120 V AC)
Power dissipation SLEEP MODE< 5 W (230 V AC)
Crest factortyp. 1.54 (120 V AC)
Crest factortyp. 1.56 (230 V AC)
Rise time< 1 s (UOut = 10 % ... 90 %)
Connection in parallelyes, for redundancy and increased capacity
Connection in seriesyes

Signal

Signal ground SGndReference potential for Out1, Out2, and Rem

Signal Out 1 (configurable)

Digital24 V DC 20 mA
Default24 V DC 20 mA 24 V DC for UOut > 0.9 x USet

Signal Out 2 (configurable)

Digital24 V DC 20 mA
Analog4 mA ... 20 mA ±5 % (Load ≤400 Ω)
Default24 V DC 20 mA 24 V DC for POut < PN

Signal relay 13/14 (configurable)

Defaultclosed (Uout > 0.9 USet)

Input

Connection MethodScrew connection
Conductor cross section, rigid min.0.2 mm²
Conductor cross section, rigid max.6 mm²
Conductor cross section flexible min.0.2 mm²
Conductor cross section flexible max.4 mm²
Single conductor/flexible terminal point with ferrule with plastic sleeve, min.0.25 mm²
Single conductor/flexible terminal point with ferrule with plastic sleeve, max.6 mm²
Single conductor/flexible terminal point with ferrule without plastic sleeve, min.0.25 mm²
Single conductor/flexible terminal point with ferrule without plastic sleeve, max.4 mm²
Conductor cross section AWG min.30
Conductor cross section AWG max.10
Stripping length6.5 mm
Tightening torque, min0.5 Nm
Tightening torque max0.6 Nm

Output

Connection MethodScrew connection
Conductor cross section, rigid min.0.2 mm²
Conductor cross section, rigid max.2.5 mm²
Conductor cross section flexible min.0.2 mm²
Conductor cross section flexible max.2.5 mm²
Single conductor/flexible terminal point with ferrule with plastic sleeve, min.0.25 mm²
Single conductor/flexible terminal point with ferrule with plastic sleeve, max.2.5 mm²
Single conductor/flexible terminal point with ferrule without plastic sleeve, min.0.25 mm²
Single conductor/flexible terminal point with ferrule without plastic sleeve, max.2.5 mm²
Conductor cross section AWG min.30
Conductor cross section AWG max.10
Stripping length6.5 mm
Tightening torque, min0.5 Nm
Tightening torque max0.6 Nm

Signal

Connection MethodPush-in connection
Conductor cross section, rigid min.0.2 mm²
Conductor cross section, rigid max.1 mm²
Conductor cross section flexible min.0.2 mm²
Conductor cross section flexible max.1.5 mm²
Single conductor/flexible terminal point with ferrule with plastic sleeve, min.0.2 mm²
Single conductor/flexible terminal point with ferrule with plastic sleeve, max.0.75 mm²
Single conductor/flexible terminal point with ferrule without plastic sleeve, min.0.2 mm²
Single conductor/flexible terminal point with ferrule without plastic sleeve, max.1.5 mm²
Conductor cross section AWG min.24
Conductor cross section AWG max.16
Stripping length8 mm

Signaling

Types of signalingLED
Types of signalingFloating signal contact
Types of signalingActive signal output Out1 (digital, configurable)
Types of signalingActive signal output Out2 (analog, configurable)
Types of signalingRemote contact
Types of signalingSignal ground SGnd

Signal output

POut> 100 % (LED lights up yellow, output power > 480 W)
POut> 75 % (LED lights up green, output power > 360 W)
POut> 50 % (LED lights up green, output power > 240 W)
UOut> 0.9 x USet (LED lights up green)
UOut< 0.9 x USet (LED flashes green)

Electrical properties

Number of phases1.00
Insulation voltage input/output4 kV AC (type test)
Insulation voltage input/output2 kV AC (routine test)
Insulation voltage output / PE0.5 kV DC (type test)
Insulation voltage output / PE0.5 kV DC (routine test)
Insulation voltage input / PE3.5 kV AC (type test)
Insulation voltage input / PE2.4 kV AC (routine test)
Switching frequency90.00 kHz ... 110.00 kHz (Auxiliary converter stage)
Switching frequency70.00 kHz ... 330.00 kHz (Main converter stage)
Switching frequency50.00 kHz ... 70.00 kHz (PFC stage)

Product properties

Product familyQUINT POWER
MTBF (IEC 61709, SN 29500)> 1100000 h (25 °C)
MTBF (IEC 61709, SN 29500)> 676000 h (40 °C)
MTBF (IEC 61709, SN 29500)> 317000 h (60 °C)
Environmental protection directiveRoHS Directive 2011/65/EU
Environmental protection directiveWEEE
Environmental protection directiveReach

Insulation characteristics

Protection classI
Degree of pollution2

Life expectancy (electrolytic capacitors)

Current5 A
Temperature40 °C
Time420000 h
Additional text120 V AC
Current5 A
Temperature40 °C
Time484000 h
Additional text230 V AC
Current10 A
Temperature25 °C
Time526000 h
Additional text120 V AC
Current10 A
Temperature25 °C
Time827000 h
Additional text230 V AC
Current10 A
Temperature40 °C
Time186000 h
Additional text120 V AC
Current10 A
Temperature40 °C
Time292000 h
Additional text230 V AC

Dimensions

Width70 mm
Height130 mm
Depth125 mm

Installation dimensions

Installation distance right/left5 mm / 5 mm
Installation distance top/bottom50 mm / 50 mm

Alternative assembly

Width122 mm
Height130 mm
Depth73 mm

Mounting

Mounting TypeDIN rail mounting
Assembly instructionsalignable: PN ≥50%, 5 mm horizontally, 15 mm next to active components, 50 mm verticallyalignable: PN <50%, 0 mm horizontally, 40 mm vertically top, 20 mm vertically bottom
Mounting Positionhorizontal DIN rail NS 35, EN 60715
With protective coatingNo

Material specifications

Flammability rating according to UL 94 (housing / terminal blocks)V0
Housing MaterialMetal
Hood versionStainless steel X6Cr17
Side element versionAluminum

Ambient conditions

Degree of ProtectionIP20
Ambient Temperature (Operation)-25 °C ... 70 °C (> 60 °C Derating: 2,5 %/K)
Ambient temperature (storage/transport)-40 °C ... 85 °C
Ambient temperature (start-up type tested)-40 °C
Maximum altitude≤ 5000 m (> 2000 m, observe derating)
Climatic class3K3 (in acc. with EN 60721)
Max. permissible relative humidity (operation)≤ 95 % (at 25 °C, non-condensing)
Shock18 ms, 30g, in each space direction (according to IEC 60068-2-27)
Vibration (Operation)5 Hz ... 100 Hz resonance search 2.3g, 90 min., resonance frequency 2.3g, 90 min. (according to DNV GL Class C)

Standards and Regulations

Rail applicationsEN 50121-3-2
Rail applicationsEN 50121-4
Rail applicationsEN 50121-5
Rail applicationsIEC 62236-3-2
Rail applicationsIEC 62236-4
Rail applicationsIEC 62236-5
HART FSK Physical Layer Test Specification ComplianceOutput voltage UOut compliant
Standard – Limitation of mains harmonic currentsEN 61000-3-2
Standard - Electrical safetyIEC 61010-2-201 (SELV)
Standard – Safety extra-low voltageIEC 61010-1 (SELV)
Standard – Safety extra-low voltageIEC 61010-2-201 (PELV)
Standard - Safe isolationIEC 61558-2-16
Standard - Safe isolationIEC 61010-2-201
Standard - safety for equipment for measurement, control, and laboratory useIEC 61010-1
Standard - Safety of transformersEN 61558-2-16
Battery chargingDIN 41773-1
Approval - requirement of the semiconductor industry with regard to mains voltage dipsSEMI F47-0706, EN 61000-4-11

Overvoltage category

EN 61010-1II (≤ 5000 m)
EN 62477-1III (≤ 2000 m)

Approvals

CSACAN/CSA-C22.2 No. 60950-1-07
CSACSA-C22.2 No. 107.1-01
Shipbuilding approvalDNV GL, PRS, BV, LR, ABS
UL approvalsUL Listed UL 508
UL approvalsUL/C-UL Recognized UL 60950-1
UL approvalsUL ANSI/ISA-12.12.01 Class I, Division 2, Groups A, B, C, D (Hazardous Location)

EMC data

Low Voltage DirectiveConformance with Low Voltage Directive 2014/35/EC
EMC requirements for noise emissionEN 61000-6-3
EMC requirements for noise emissionEN 61000-6-4
EMC requirements for noise immunityEN 61000-6-1
EMC requirements for noise immunityEN 61000-6-2
Electromagnetic compatibilityConformance with EMC Directive 2014/30/EU
EMC requirements, power plantIEC 61850-3
EMC requirements, power plantEN 61000-6-5
Conducted noise emissionEN 55016
Conducted noise emissionEN 61000-6-3 (Class B)
Noise emissionAdditional basic standard EN 61000-6-5 (immunity in power station), IEC/EN 61850-3 (energy supply)
Noise emissionEN 55016
Noise emissionEN 61000-6-3 (Class B)
DNV GL conducted interferenceClass A
Additional textArea power distribution
DNV GL noise radiationClass B
Additional textBridge and deck area

Harmonic currents

Standards/regulationsEN 61000-3-2
Standards/regulationsEN 61000-3-2 (Class A)
Frequency Range0 kHz ... 2 kHz

Flicker

Standards/regulationsEN 61000-3-3
Standards/regulationsEN 61000-3-3
Frequency Range0 kHz ... 2 kHz

Electrostatic discharge

Standards/regulationsEN 61000-4-2
Contact discharge8 kV (Test Level 4)
Discharge in air15 kV (Test Level 4)
CommentsCriterion A

Electromagnetic HF field

Standards/regulationsEN 61000-4-3
Frequency Range80 MHz ... 1 GHz
Test field strength20 V/m (Test Level 3)
Frequency Range1 GHz ... 6 GHz
Test field strength10 V/m (Test Level 3)
Frequency Range1 GHz ... 6 GHz
Test field strength10 V/m (Test Level 3)
CommentsCriterion A

Fast transients (burst)

Standards/regulationsEN 61000-4-4
Input4 kV (Test Level 4 - asymmetrical)
Output4 kV (Test Level 4 - asymmetrical)
Signal4 kV (Test Level 4 - asymmetrical)
CommentsCriterion A

Surge voltage load (surge)

Standards/regulationsEN 61000-4-5
Input3 kV (Test Level 4 - symmetrical)
Input6 kV (Test Level 4 - asymmetrical)
Output1 kV (Test Level 3 - symmetrical)
Output2 kV (Test Level 3 - asymmetrical)
Signal1 kV (Test Level 2 - asymmetrical)
CommentsCriterion A

Conducted interference

Standards/regulationsEN 61000-4-6
I/O/Sasymmetrical
Frequency Range0.15 MHz ... 80 MHz
CommentsCriterion A
Voltage10 V (Test Level 3)

Power frequency magnetic field

Standards/regulationsEN 61000-4-8
Frequency16.7 Hz
Frequency50 Hz
Frequency60 Hz
Test field strength100 A/m
Additional text60 s
CommentsCriterion A
Frequency50 Hz
Frequency60 Hz
Frequency Range50 Hz ... 60 Hz
Test field strength1 kA/m
Additional text3 s
Frequency0 Hz
Test field strength300 A/m
Additional textDC, 60 s

Voltage dips

Standards/regulationsEN 61000-4-11
Voltage230 V AC
Frequency50 Hz
Voltage dip70 %
Number of periods0.5 / 1 / 25 periods
Additional textTest Level 2
CommentsCriterion A: 0.5 / 1 / 25 periods
Voltage dip40 %
Number of periods5 / 10 / 50 periods
Additional textTest Level 2
CommentsCriterion A
Voltage dip0 %
Number of periods0,5 / 1 / 5 / 50 / 250 periods
Additional textTest Level 2
CommentsCriterion A: 0.5 / 1 periodCriterion B: 5 / 50 / 250 periods

Pulse-shape magnetic field

Standards/regulationsEN 61000-4-9
Test field strength1000 A/m
CommentsCriterion A

Attenuated sinusoidal oscillations (ring wave)

Standards/regulationsEN 61000-4-12
Input2 kV (Test Level 4 - symmetrical)
Input4 kV (Test Level 4 - asymmetrical)
CommentsCriterion A

Asymmetrical conducted disturbance variables

Standards/regulationsEN 61000-4-16
Test level 115 Hz 150 Hz (Test Level 4)
Voltage30 V 3 V
Test level 2150 Hz 1.5 kHz (Test Level 4)
Voltage3 V
Test level 31.5 kHz 15 kHz (Test Level 4)
Voltage3 V 30 V
Test level 415 kHz 150 kHz (Test Level 4)
Voltage30 V
Test level 516.7 Hz 50 Hz 60 Hz (Test Level 4)
Voltage30 V (Permanent)
Test level 616.7 Hz 50 Hz 60 Hz (Test Level 4)
Voltage300 V (1 s)
CommentsCriterion A

Attenuated oscillating wave

Standards/regulationsEN 61000-4-18
Input, output (test level 1)100 kHz 1 MHz (Test Level 3 - symmetrical)
Voltage1 kV
Input, output (test level 2)10 MHz
Voltage1 kV
Input, output (test level 3)100 kHz 1 MHz (Test Level 3 - asymmetrical)
Voltage2.5 kV
Signals (test level 1)100 kHz 1 MHz (Test Level 3 - symmetrical)
Voltage1 kV
Signals (test level 2)100 kHz 1 MHz (Test Level 3 - asymmetrical)
Voltage2.5 kV
CommentsCriterion A

Attenuated oscillating magnetic field

Standards/regulationsEN 61000-4-10
Test field strength110 A/m
Test level 1100 kHz
Test field strength110 A/m
Test level 21 MHz
CommentsCriterion A

Criteria

Criterion ANormal operating behavior within the specified limits.
Criterion BTemporary impairment to operational behavior that is corrected by the device itself.
Criterion CTemporary adverse effects on the operating behavior, which the device corrects automatically or which can be restored by actuating the operating elements.
Accessories
  • Phoenix Contact2938235
    2938235
    2938235 - Universal wall adapter for securely mounting the device in the event of strong vibrations. The device is screwed directly onto the mounting surface. The universal wall adapter is attached on the top/bottom.
  • Phoenix Contact2901664
    2901664
    2901664 - 2-piece universal wall adapter for securely mounting the device in the event of strong vibrations. The profiles that are screwed onto the side of the device are screwed directly onto the mounting surface. The universal wall adapter is attached on the left/right.
  • Phoenix Contact2938196
    2938196
    2938196 - Assembly adapter for QUINT-PS... power supply on S7-300 rail
  • Phoenix Contact2909681
    2909681
    Programming adapter - TWN4 MIFARE NFC USB ADAPTER
  • Phoenix Contact2907919
    2907919
    2907919 - Type 2/3 surge protection, consisting of protective plug and base element with screw connection. For single-phase power supply network with integrated status indicator and remote signaling. Nominal voltage: 230 V AC/DC
  • Phoenix Contact2907917
    2907917
    2907917 - Type 3 surge protection, consisting of protective plug and base element, with integrated status indicator and remote signaling for single-phase power supply networks. Nominal voltage: 60 V AC/DC
  • Phoenix Contact2907928
    2907928
    2907928 - Type 2/3 surge protection, consisting of protective plug and base element with Push-in connection. For single-phase power supply network with integrated status indicator and remote signaling. Nominal voltage: 230 V AC/DC

Why Proax for Phoenix Contact 2904611?

Proax is an authorized distributor of Phoenix Contact 2904611 and one of Phoenix Contact's largest distributors in North America. Our highly skilled in-house technical team is ready to assist with any technical needs.

Have a question in mind? to help you get the right product as quickly as possible for your project. We're always here to help!

Short Lead Time
Highly Trained Staff
Live Chat
Technical Support
Local Inventory
60+ Years Experience
Additional Information

Pack Size1
Recommended
  • Phoenix Contact2904626
    2904626
    2904626 - Primary-switched QUINT POWER power supply with free choice of output characteristic curve, SFB (selective fuse breaking) technology, NFC interface, and protective coating, input: 1-phase, output: 48 V DC / 10 A
  • Phoenix Contact2904612
    2904612
    Alimentation QUINT POWER à découpage primaire avec caractéristique de sortie au choix, SFB Technology (Selective Fuse Breaking) et interface NFC, entrée : monophasée, sortie : 48 V DC / 20 A
  • Phoenix Contact2904610
    2904610
    2904610 - Primary-switched QUINT POWER power supply for DIN rail mounting with free choice of output characteristic curve and SFB (Selective Fuse Breaking) technology, input: 1-phase, output: 48 V DC / 5 A
  • Phoenix Contact2909575
    2909575
    2909575 - Primary-switched power supply unit QUINT POWER, Push-in connection, DIN rail mounting, input: 1-phase, output: 24 V DC / 1.3 A
  • Phoenix Contact2904597
    2904597
    2904597 - Primary-switched power supply unit QUINT POWER, Screw connection, DIN rail mounting, input: 1-phase, output: 24 V DC / 1.3 A
  • Phoenix Contact2904601
    2904601
    2904601 - Primary-switched QUINT POWER power supply with free choice of output characteristic curve, SFB (selective fuse breaking) technology, and NFC interface, input: 1-phase, output: 24 V DC/10 A
  • Phoenix Contact2904616
    2904616
    Alimentation QUINT POWER à découpage primaire pour montage sur rail DIN, avec caractéristique de sortie au choix et SFB Technology (Selective Fuse Breaking), vernis de protection et Mosfet de découplage intégré, entrée : monophasée, sortie : 24 V DC/10 A
  • Phoenix Contact2904625
    2904625
    Power supply unit - QUINT4-PS/1AC/24DC/10/CO
  • Phoenix Contact2909576
    2909576
    2909576 - Primary-switched power supply unit QUINT POWER, Push-in connection, DIN rail mounting, input: 1-phase, output: 24 V DC / 2.5 A
  • Phoenix Contact2904598
    2904598
    2904598 - Primary-switched power supply unit QUINT POWER, Screw connection, DIN rail mounting, input: 1-phase, output: 24 V DC / 2.5 A. Alternative item: 2909576
  • Phoenix Contact2904602
    2904602
    Power supply unit - QUINT4-PS/1AC/24DC/20
  • Phoenix Contact2904617
    2904617
    Power supply unit - QUINT4-PS/1AC/24DC/20/+
  • Phoenix Contact2909577
    2909577
    Power supply unit - QUINT4-PS/1AC/24DC/3.8/PT
  • Phoenix Contact2904599
    2904599
    Power supply unit - QUINT4-PS/1AC/24DC/3.8/SC
  • Phoenix Contact2904603
    2904603
    2904603 - Primary-switched QUINT POWER power supply with free choice of output characteristic curve, SFB (selective fuse breaking) technology, and NFC interface, input: 1-phase, output: 24 V DC/40 A
  • Phoenix Contact2904618
    2904618
    QUINT4-PS/1AC/24DC/40/+ - Power supply unit
  • Phoenix Contact2904600
    2904600
    2904600 - Primary-switched QUINT POWER power supply with free choice of output characteristic curve, SFB (selective fuse breaking) technology, and NFC interface, input: 1-phase, output: 24 V DC/5 A
  • Phoenix Contact2904595
    2904595
    2904595 - Primary-switched power supply unit QUINT POWER, Push-in connection, DIN rail mounting, input: 1-phase, output: 5 V DC / 5 A
  • Phoenix Contact2904608
    2904608
    2904608 - Primary-switched QUINT POWER power supply with free choice of output characteristic curve, SFB (Selective Fuse Breaking) Technology, and NFC interface, input: 1-phase, output: 12 V DC / 15 A
  • Phoenix Contact2904605
    2904605
    2904605 - Primary-switched power supply unit QUINT POWER, Push-in connection, DIN rail mounting, input: 1-phase, output: 12 V DC / 2.5 A

Not in stock

Request lead time or order—we'll ensure quick delivery

Phoenix Contact Availability