Puls QS20.241, QS20.241-A1, QS20.241-C1 Data Sheet

QS20.241, QS20.241-A1, QS20.241-C1

P

G

S

Output voltage

DC 24V

Adjustment range

Output current

20 – 17A

continuous

30 – 26A

for typ. 4s

Output power

480W

continuous

for typ. 4s

Output ripple

20Hz to 20MHz

Input voltage

±

Mains frequency

50-60Hz

±6%

AC Input current

4.56 / 2.48A

at 120 / 230Vac

Power factor

0.95 / 0.90

at 120 / 230Vac

AC Inrush current

typ. 9 / 7A peak

at 120 / 230Vac

Efficiency

92.4 / 93.9%

at 120 / 230Vac

Losses

at

Temperature range

Derating

12W/°C

+60 to +70°C

Hold-up time

typ. 32 / 51ms

at 120 / 230Vac

Dimensions

82x124x127mm

WxHxD

O

M

IND. CONT. EQ.

Q-Series

ENERAL DESCRIPTION

The most outstanding features of this Dimension Q­Series DIN-rail power supply are the high efficiency and
the small size, which are achieved by a synchronous
rectification and further novel design details.

With short-term peak power capability of 150% and
built-in large sized output capacitors, these features
help start motors, charge capacitors and absorb reverse
energy and often allow a unit of a lower wattage class
to be used.

High immunity to transients and power surges as well as
low electromagnetic emission makes usage in nearly
every environment possible.

The integrated output power manager, a wide range
input voltage design and virtually no input inrush
current make installation and usage simple. Diagnostics
are easy due to the dry DC-ok contact, a green DC-ok
LED and red overload LED.

Unique quick-connect spring-clamp terminals allow a
safe and fast installation and a large international
approval package for a variety of applications makes
this unit suitable for nearly every situation.

24V, 20A, SINGLE PHASE INPUT

OWER SUPPLY

 AC 100-240V Wide-range Input
 Width only 82mm
 Efficiency up to 93.9%
 ATEX and IECEx Approved (-A1 Version)
 -C1 Version with Conformal Coated PC-board
 150% (720W) Peak Load Capability
 Safe Hiccup
 Easy Fuse Tripping due to High Overload Current
 Active Power Factor Correction (PFC)
 Negligible low Inrush Current Surge
 Short-term Operation down to 60Vac and up to 300Vac
 Full Power Between -25°C and +60°C
 DC-OK Relay Contact
 Quick-connect Spring-clamp Terminals
 3 Year Warranty

PLUS

Overload Mode

HORT-FORM DATA

24 - 28V

720W

< 100mVpp

AC 100-240V

39.6 / 31.4W

-25°C to +70°C operational

15%

120 / 230Vac

RDER NUMBERS

Power Supply QS20.241 24-28V Standard unit

Accessory ZM2.WALL Wall mount bracket

Sep. 2019 / Rev. 2.3 DS-QS20.241-EN
All parameters are specified at 24V, 20A, 230Vac, 25°C ambient and after a 5 minutes run-in time unless otherwise noted.

ARKINGS

QS20.241-A1 ATEX approved unit
QS20.241-C1 Conformal coated unit

ZM15.SIDE Side mount bracket
YR40.242 Redundancy module
YR40.245 Redundancy module

UL 508

IECEx ATEX

II 3G Ex ec nC II T3 Gc

UL 60950-1

Class I Div 2

EMC, LVD, RoHS

Marine

1/26

QS20.241, QS20.241-A1, QS20.241-C1

I

T

Q-Series

NDEX

Page Page

1. Intended Use .......................................................3

2. Installation Requirements ...................................3

3. AC-Input...............................................................4

4. DC-Input...............................................................5

5. Input Inrush Current ...........................................5

6. Output .................................................................6

7. Hold-up Time .......................................................8

8. DC-OK Relay Contact ..........................................8

9. Efficiency and Power Losses................................9

10. Lifetime Expectancy and MTBF ......................... 10

11. Functional Diagram ........................................... 10

12. Terminals and Wiring ........................................ 11

13. Front Side and User Elements ........................... 12

14. EMC .................................................................... 13

15. Environment ...................................................... 14

16. Protection Features ........................................... 15

17. Safety Features .................................................. 15

18. Dielectric Strength ............................................ 16

19. Approvals ........................................................... 17

20. Physical Dimensions and Weight ...................... 18

24V, 20A, SINGLE PHASE INPUT

21. Accessories ........................................................ 19

21.1. ZM2.WALL Wall Mounting Bracket ....... 19

21.2. ZM15.SIDE Side Mounting Bracket ........ 19

21.3. YR40 Redundancy Modules ..................... 20

22. Application Notes ............................................. 21

22.1. Repetitive Pulse Loading .......................... 21

22.2. Peak Current Capability ........................... 22

22.3. Back-feeding Loads .................................. 22

22.4. External Input Protection ......................... 22

22.5. Charging of Batteries ............................... 23

22.6. Output Circuit Breakers ............................ 23

22.7. Parallel Use to Increase Output Power .... 24

22.8. Parallel Use for Redundancy .................... 24

22.9. Series Operation ....................................... 25

22.10. Inductive and Capacitive Loads................ 25

22.11. Operation on Two Phases ........................ 25

22.12. Use in a Tightly Sealed Enclosure ............ 25

22.13. Mounting Orientations ............................ 26

The information presented in this document is believed to be accurate and reliable and may change without notice.
No part of this document may be reproduced or utilized in any form without permission in writing from the publisher.

ERMINOLOGY AND ABREVIATIONS

PE and symbol PE is the abbreviation for Protective Earth and has the same meaning as the symbol .

Earth, Ground This document uses the term “earth” which is the same as the U.S. term “ground”.

T.b.d. To be defined, value or description will follow later.

AC 230V A figure displayed with the AC or DC before the value represents a nominal voltage with

standard tolerances (usually ±15%) included.
E.g.: DC 12V describes a 12V battery disregarding whether it is full (13.7V) or flat (10V)

230Vac A figure with the unit (Vac) at the end is a momentary figure without any additional

tolerances included.

50Hz vs. 60Hz As long as not otherwise stated, AC 230V parameters are valid at 50Hz mains frequency.

may A key word indicating flexibility of choice with no implied preference.

shall A key word indicating a mandatory requirement.

should A key word indicating flexibility of choice with a strongly preferred implementation.

Sep. 2019 / Rev. 2.3 DS-QS20.241-EN
All parameters are specified at 24V, 20A, 230Vac, 25°C ambient and after a 5 minutes run-in time unless otherwise noted.

2/26

QS20.241, QS20.241-A1, QS20.241-C1

1. I

2. I

WARNING

Q-Series

24V, 20A, SINGLE PHASE INPUT

NTENDED USE

This device is designed for installation in an enclosure and is intended for the general use such as in industrial control,
office, communication, and instrumentation equipment.

Do not use this power supply in equipment, where malfunction may cause severe personal injury or threaten human
life.

This device is designed for use in hazardous, non-hazardous, ordinary or unclassified locations.

NSTALLATION REQUIREMENTS

This device may only be installed and put into operation by qualified personnel.
This device does not contain serviceable parts. The tripping of an internal fuse is caused by an internal defect.
If damage or malfunction should occur during installation or operation, immediately turn power off and send unit to

the factory for inspection.
Mount the unit on a DIN-rail so that the output terminals are located on the top and the input terminals are located

on the bottom of the unit. For other mounting orientations see de-rating requirements in this document. See chapter

22.13.
This device is designed for convection cooling and does not require an external fan. Do not obstruct airflow and do

not cover ventilation grid (e.g. cable conduits) by more than 30%!
Keep the following installation clearances: 40mm on top, 20mm on the bottom, 5mm on the left and right sides are

recommended when the device is loaded permanently with more than 50% of the rated power. Increase this clearance
to 15mm in case the adjacent device is a heat source (e.g. another power supply).

A disconnecting means shall be provided for the output of the power supplies when used in applications according to
CSA C22.2 No 107.1-01.

Risk of electrical shock, fire, personal injury or death.

- Do not use the power supply without proper grounding (Protective Earth). Use the terminal on the input block for
earth connection and not one of the screws on the housing.

- Turn power off before working on the device. Protect against inadvertent re-powering.

- Make sure that the wiring is correct by following all local and national codes.

- Do not modify or repair the unit.

- Do not open the unit as high voltages are present inside.

- Use caution to prevent any foreign objects from entering the housing.

- Do not use in wet locations or in areas where moisture or condensation can be expected.

- Do not touch during power-on, and immediately after power-off. Hot surfaces may cause burns.

Notes for use in hazardous location areas:

The power supply is suitable for use in Class I Division 2 Groups A, B, C, D locations.
Additionally, the QS20.241-A1 is suitable for use in Group II Category 3 (Zone 2) environments and is evaluated

according to EN 60079-0:2009 and EN 60079-15:2010.

WARNING EXPLOSION HAZARDS!

Substitution of components may impair suitability for this environment. Do not disconnect the unit or operate the
voltage adjustment unless power has been switched off or the area is known to be non-hazardous.

A suitable enclosure must be provided for the end product which has a minimum protection of IP54 and fulfils the
requirements of the EN 60079-15.

Sep. 2019 / Rev. 2.3 DS-QS20.241-EN
All parameters are specified at 24V, 20A, 230Vac, 25°C ambient and after a 5 minutes run-in time unless otherwise noted.

3/26

QS20.241, QS20.241-A1, QS20.241-C1

3. AC-I

AC input

AC

Allowed voltage

Input frequency

nom.

50–60Hz

±6%

Turn

Shut

Input current

Power factor *)

Crest factor **)

Start

Rise time

Turn

Turn-on

85V

Rated

input range

max.

500ms

V

IN

P

OUT

60V 300Vac

276V

Shut-down

full

power

for

200ms

Start-up

delay

Rise

Time

Overshoot

- 5%

Output
Voltage

Input
Voltage

20A

2 4 6 8 10 12 14 16 18

0

1

2

3

4

5

6A

Output Current

Input Current, typ.

230Vac

120Vac

100Vac

Power Factor, typ.

2 4 6 8 10 12 14 16 18 20A

0.75

0.8

0.85

0.9

0.95

1.0

Output Current

230Vac

100Vac
120Vac

Q-Series

24V, 20A, SINGLE PHASE INPUT

NPUT

nom. AC 100-240V suitable for TN-, TT- and IT mains networks

input range min. 85-276Vac continuous operation

min. 60-85Vac full power for 200ms, no damage between 0 and 85Vac
min. 276-300Vac < 500ms

L or N to earth max. 276Vac continuous, IEC 62103

-on voltage typ. 77Vac steady-state value, see Fig. 3-1

-down voltage typ. 73Vac steady-state value, see Fig. 3-1
typ. 53Vac dynamic value

AC 100V AC 120V AC 230V

typ. 5.47A 4.56A 2.48A at 24V, 20A, see Fig. 3-3

typ. 0.96 0.95 0.90 at 24V, 20A, see Fig. 3-4
typ. 1.6 1.7 2.05 at 24V, 20A

-up delay typ. 640ms 610ms 660ms see Fig. 3-2

typ. 80ms 80ms 80ms 0mF, 24V, 20A, see Fig. 3-2

typ. 85ms 85ms 85ms 20mF, 24V, 20A, see Fig. 3-2

-on overshoot max. 100mV 100mV 100mV see Fig. 3-2

*) The power factor is the ratio of the true (or real) power to the apparent power in an AC circuit.
**) The crest factor is the mathematical ratio of the peak value to RMS value of the input current waveform.

Fig. 3-3 Input current vs. output load at 24V Fig. 3-4 Power factor vs. output load

Sep. 2019 / Rev. 2.3 DS-QS20.241-EN
All parameters are specified at 24V, 20A, 230Vac, 25°C ambient and after a 5 minutes run-in time unless otherwise noted.

Fig. 3-1 Input voltage range Fig. 3-2 Turn-on behavior, definitions

4/26

QS20.241, QS20.241-A1, QS20.241-C1

4. DC-I

DC input

DC input range

DC in

Allowed Voltage L/N to Earth

Turn

Shut-down voltage

typ.

69Vdc

steady state value

+

-

Load

L

PE

+

-

Power Supply

AC

DC

Battery

N

5. I

Inrush current

Inrush energy
Inrush delay (A)

Q-Series

NPUT

nom. DC 110-150V -20%/+25%

min. 88-187Vdc

put current typ. 4.6A 110Vdc, at 24V, 20A

max. 375Vdc IEC 62103

-on voltage typ. 74Vdc steady state value

Fig. 4-1 Wiring for DC Input

Instructions for DC use:

a) Use a battery or similar DC source.

For other sources contact PULS
b) Conne
c) Connect the PE terminal to an earth wire or to the

ct +pole to L and –pole to N.

machine ground.

24V, 20A, SINGLE PHASE INPUT

NPUT INRUSH CURRENT

An active inrush limitation circuit limits the input inrush current after turn-on of the input voltage and after short
input voltage interruptions.

The charging current into EMI suppression capacitors is disregarded in the first microseconds after switch-on.

AC 100V AC 120V AC 230V

max. 13A

typ. 11A

max. 5A2s 5A2s 5A2s over entire temperature range;

typ. 400ms 400ms 650ms see (A) in Fig. 5-1

Fig. 5-1 Input inrush current, typical behavior

13A

peak

9A

peak

A…. Inrush delay

Input: 230Vac
Output: 24V, 20A
Ambient: 25°C
Upper curve: Input current 5A / DIV
Middle curve: Input voltage 500V / DIV
Lower curve: Output voltage 20V / DIV
Time basis: 100ms / DIV

13A

peak

7A

peak

over entire temperature range;

peak

over entire temperature range;

peak

mains interruptions > 750ms

mains interruptions > 750ms

mains interruptions > 750ms

Sep. 2019 / Rev. 2.3 DS-QS20.241-EN
All parameters are specified at 24V, 20A, 230Vac, 25°C ambient and after a 5 minutes run-in time unless otherwise noted.

5/26

QS20.241, QS20.241-A1, QS20.241-C1

6. O

Output voltage

Adjustment range

Factory setting

Line regulation

Load regulation

Ripple and noise voltage

Output current

Outpu

BonusPower

max.

4.5s

BonusPower

Overload behaviour

Short

Output capacitance

Q-Series

24V, 20A, SINGLE PHASE INPUT

UTPUT

nom. 24V

min. 24-28V guaranteed

max. 30V

typ. 24.1V ±0.2%, at full load, cold unit

max. 10mV 60-300Vac

max. 100mV static value, 0A  20A

max. 100mVpp 20Hz to 20MHz, 50Ohm

nom. 20A continuously available at 24V, see Fig. 6-1
nom. 17A continuously available at 28V, see Fig. 6-1
nom. 30A

nom. 26A

t power nom. 480W continuously available

nom. 720W *) short term available BonusPower

®

time typ. 4s duration until the output voltage dips, see Fig. 6-2

min. 3.5s

****)

*)

short term available BonusPower

at clockwise end position of potentiometer

at 24V, for typical 4s, see Fig. 6-1

*)

short term available BonusPower

at 28V, for typical 4s, see Fig. 6-1

® *)

® *)

® *)

,

,

®

recovery time typ. 7s overload free time to reset power manager Fig. 6-4

cont. current output voltage > 20Vdc, see Fig. 6-1

Hiccup

-circuit current min. 30A
max. 40A
max. 14A

PLUS

***)

load impedance 50mOhm, see Fig. 6-3

***)

load impedance 50mOhm, see Fig. 6-3

***)

average (R.M.S.) current, load impedance <10mOhm,

mode

**)

output voltage < 20Vdc, see Fig. 6-1

see Fig. 6-3

typ. 8 500µF included inside the power supply

*) BonusPower®, short term power capability (up to typ. 4s)

The power supply is designed to support loads with a higher short-term power requirement without damage or shutdown. The short­term duration is hardware controlled by an output power manager. This BonusPower
can be found in chapter 22.1. If the power supply is loaded longer with the BonusPower
Fig. 6-2), the max. output power is automatically reduced to 480W. If the power requirement is continuously above 480W and the
voltage falls below approx. 20V (due to the current regulating mode at overload), the unit shuts-off and makes periodical restart
attempts. This behaviour is called hiccup mode, which is described below. If the voltage is above 20V, the unit continuously delivers
current.

PLUS

**) Hiccup

At heavy overloads (when output voltage falls below 20V), the power supply delivers continuous output current for 2s. After this, the
output is switched off for approx. 17s before a new start attempt is automatically performed. This cycle is repeated as long as the
overload exists. If the overload has been cleared, the device will operate normally. See also Fig. 6-3.
During the off-period a small rest voltage and rest current is present on the output.

***) Discharge current of output capacitors is not included.

****) This is the maximum output voltage which can occur at the clockwise end position of the potentiometer due to tolerances. It is not

guaranteed value which can be achieved. The typical value is about 28.5V.

Mode

®

is repeatedly available. Detailed information

®

than shown in the Bonus-time diagram (see

Sep. 2019 / Rev. 2.3 DS-QS20.241-EN
All parameters are specified at 24V, 20A, 230Vac, 25°C ambient and after a 5 minutes run-in time unless otherwise noted.

6/26

QS20.241, QS20.241-A1, QS20.241-C1

Peak current voltage dips

Output Voltage

0

0 5 10 20 25

4

8

12

28V

16

20

24

40A15 30

Output
Current

35

A

B

A

B

Short term <5s then auto
switching to curve +

Below 20Vdc hiccup mode

C

C

Continuously available

B

C

0
528W 576W 624W 672W 720W

768W

1

2

3

7

4

5

6

8

9

10s

Output Power

min

max

typ

Output
Current

0

35A

17s

17s17s 2s 2s2s

t

Start of
short circuit

End of

short circuit

Power
Demand

100%

t

t

L

imitation by

Power Manager

Output
Voltage

Bonus Power disabled

Bonus

Time

Recovery Time

100%

Output
Voltage

Input
Voltage

Bonus

Power

Output
Power

150%

Short of

Output

100%

Output
Voltage

Bonus

Power

Output
Power

150%

Q-Series

24V, 20A, SINGLE PHASE INPUT

Peak current capability (up to several milliseconds)

The power supply can deliver a peak current which is higher than the specified short term current. This helps to start
current demanding loads or to safely operate subsequent circuit breakers.

The extra current is supplied by the output capacitors inside the power supply. During this event, the capacitors will be
discharged and causes a voltage dip on the output. Detailed curves can be found in chapter 22.2.

typ. from 24V to 20V at 40A for 50ms, resistive load
typ. from 24V to 17V at 100A for 2ms, resistive load
typ. from 24V to 16V at 100A for 5ms, resistive load

Fig. 6-1 Output voltage vs. output current,

typ.

Fig. 6-2 Bonus time vs. output power

Fig. 6-3 Short-circuit on output, hiccup mode (typ.) Fig. 6-4 BonusPower® recovery time

The BonusPower® is available as soon as power comes on and immediately after the end of an output short circuit or
output overload.

Fig. 6-5 BonusPower® after input turn-on Fig. 6-6 BonusPower® after output short

Sep. 2019 / Rev. 2.3 DS-QS20.241-EN
All parameters are specified at 24V, 20A, 230Vac, 25°C ambient and after a 5 minutes run-in time unless otherwise noted.

7/26

QS20.241, QS20.241-A1, QS20.241-C1

7. H

Hold

10

20

30

40

50

100ms

85 120 155 190 230Vac

Input Voltage

24V, 20A, min.

60

70

80

Hold-up Time

90

24V, 20A, typ.

24V, 10A, min.

24V, 10A, typ.

- 5%

Hold-up Time

Zero Transition

Output
Voltage

Input
Voltage

8. DC-OK RELAY CONTACT

Contact closes

Contact opens
Contact re-closes

As soon as the output voltage exceeds 90% of the adjusted voltage.

Contact

Isolation voltage

250ms

0.9* V

ADJ

<

1ms

10%

open

V

OUT

= V

ADJ

openclosed

closed

>

1ms

Q-Series

24V, 20A, SINGLE PHASE INPUT

OLD-UP TIME

AC 100V AC 120V AC 230V

-up Time typ. 64ms 64ms 99ms at 24V, 10A, see Fig. 7-1
typ. 32ms 32ms 51ms at 24V, 20A, see Fig. 7-1

Fig. 7-1 Hold-up time vs. input voltage Fig. 7-2 Shut-down behavior, definitions

This feature monitors the output voltage, which is produced by the power supply itself. It is independent of a back-fed
voltage from a unit connected in parallel to the power supply output.

As soon as the output voltage reaches the adjusted output voltage level.
As soon as the output voltage dips more than 10% below the adjusted output voltage.

Short dips will be extended to a signal length of 250ms. Dips shorter than 1ms will be ignored.

ratings max 60Vdc 0.3A, 30Vdc 1A, 30Vac 0.5A resistive load

min 1mA at 5Vdc min. permissible load

See dielectric strength table in section 18.

Fig. 8-1 DC-ok relay contact behavior

Note: The DC-ok feature requires that the output voltage reaches the nominal (=adjusted) level after turn-on in order to function according

to specification. If this level cannot be achieved, the overload lamp will be on and the DC-ok contact will be open. The overload signal
will only shut off as soon as the adjusted voltage is reached. This is an important condition to consider particularly, if the load is a
battery, the power supply is used in parallel or the power supply is used for N+1 redundant systems.

Sep. 2019 / Rev. 2.3 DS-QS20.241-EN
All parameters are specified at 24V, 20A, 230Vac, 25°C ambient and after a 5 minutes run-in time unless otherwise noted.

8/26

QS20.241, QS20.241-A1, QS20.241-C1

9. E

Efficiency

Average efficiency *)
Power losses

Efficiency

4 6 8 10 12 14 16 18 20A

86

87

88

89

90

91

Output Current

92

93

94%

120Vac

100Vac

230Vac

Power Losses

0 2 4 6 8 10 12 14 20A

10

5

20

25

30

40

45W

120Vac

100Vac

230Vac

16 18

35

15

Output Current

Efficiency

85 120

155

190 225 260Vac

88

89

90

91

Input Voltage

92

93

94%

Power Losses

20

25

30

35

40

45

50W

85 120

155

190 225 260Vac

Input Voltage

Q-Series

24V, 20A, SINGLE PHASE INPUT

FFICIENCY AND POWER LOSSES

AC 100V AC 120V AC 230V

typ. 91.6% 92.4% 93.9% at 24V, 20A

typ. 91.0% 91.8% 92.9% 25% at 5A, 25% at 10A, 25%

at 15A. 25% at 20A

typ. 9.0W 9.2W 10.0W at 24V, 0A

typ. 44.0W 39.6W 31.4W at 24V, 20A

*) The average efficiency is an assumption for a typical application where the power supply is loaded with 25% of the nominal load for 25%

of the time, 50% of the nominal load for another 25% of the time, 75% of the nominal load for another 25% of the time and with 100%
of the nominal load for the rest of the time.

Fig. 9-1 Efficiency vs. output current at 24V,

typ

Fig. 9-2 Losses vs. output current at 24V, typ.

Fig. 9-3 Efficiency vs. input voltage at 24V,

Sep. 2019 / Rev. 2.3 DS-QS20.241-EN
All parameters are specified at 24V, 20A, 230Vac, 25°C ambient and after a 5 minutes run-in time unless otherwise noted.

20A, typ.

Fig. 9-4 Losses vs. input voltage at 24V, 20A,

typ.

9/26

QS20.241, QS20.241-A1, QS20.241-C1

10. L

MTBF

Lifetime expectancy

MTBF

MTBF

11. FUNCTIONAL DIAGRAM

+

+

-

-

Output

Over-

Voltage

Protection

PFC

Converter

Output

Voltage

Regulator

Power

Converter

Output

Filter

DC-ok
Relay

Output
Voltage
Monitor

Output

Power

Manager

Temper-

ature
Shut-

down

Input Fuse
Input Filter
Input Rectifier
Active Inrush Limiter

V

OUT

L

N

DC-ok
Contact

Overload
LED

DC-ok
LED

Q-Series

24V, 20A, SINGLE PHASE INPUT

IFETIME EXPECTANCY AND

AC 100V AC 120V AC 230V

*) 54 000h 59 000h 71 000h at 24V, 20A and 40°C

135 000h 143 000h 164 000h at 24V, 10A and 40°C

153 000h *) 165 000h *) 200 000h *) at 24V, 20A and 25°C

**) SN 29500, IEC 61709 407 000h 441 000h 469 000h at 24V, 20A and 40°C

749 000h 799 000h 840 000h at 24V, 20A and 25°C

**) MIL HDBK 217F 204 000h 215 000h 229 000h at 24V, 20A and 40°C; Ground

Benign GB40

273 000h 288 000h 308 000h at 24V, 20A and 25°C; Ground

Benign GB25

*) The Lifetime expectancy shown in the table indicates the minimum operating hours (service life) and is determined by the lifetime

expectancy of the built-in electrolytic capacitors. Lifetime expectancy is specified in operational hours and is calculated according to the
capacitor’s manufacturer specification. The manufacturer of the electrolytic capacitors only guarantees a maximum life of up to 15 years
(131 400h). Any number exceeding this value is a calculated theoretical lifetime which can be used to compare devices.

**) MTBF stands for Mean Time Between Failure, which is calculated according to statistical device failures, and indicates reliability of a

device. It is the statistical representation of the likelihood of a unit to fail and does not necessarily represent the life of a product.
The MTBF figure is a statistical representation of the likelihood of a device to fail. A MTBF figure of e.g. 1 000 000h means that
statistically one unit will fail every 100 hours if 10 000 units are installed in the field. However, it can not be determined if the failed unit
has been running for 50 000h or only for 100h.

Sep. 2019 / Rev. 2.3 DS-QS20.241-EN
All parameters are specified at 24V, 20A, 230Vac, 25°C ambient and after a 5 minutes run-in time unless otherwise noted.

Fig. 11-1 Functional diagram

10/26

QS20.241, QS20.241-A1, QS20.241-C1

12. T

Type

Solid wire

0.5-6mm2

0.5-6mm2

0.3-4mm2

Stranded wire

American Wire Gauge

Wire stripping length

Max. wire dia
(including ferrules)

Instructions:

a)

b)
c)

d
e
f

Power

Supply

+ +

- -

Input

Output

Load

+

-

max 25A!

Power
Supply

+ +

- -

Input

Output

Load

+

-

Distribution
Terminals

Power

Supply

+ +

- -

Input

Output

Power

Supply

+ +

- -

Input

Output

Q-Series

ERMINALS AND WIRING

Bi-stable, quick-connect spring clamp terminals. Shipped in open position.

- IP20 Finger safe construction.

- Suitable for field- and factory installation.

Input Output DC-OK-Signal

0.5-4mm2 0.5-4mm2 0.3-2.5mm2
20-10 AWG 20-10 AWG 26-12 AWG

10mm / 0.4inch 10mm / 0.4inch 6mm / 0.25inch

meter

Use appropriate copper cables that are designed for minimum

operating temperatures of:
60°C for ambient up to 45°C and
75°C for ambient up to 60°C minimum
90°C for ambient up to 70°C minimum.

Follow national installation codes and installation regulations!

Ensure that all strands of a stranded wire enter the terminal

connection!
) Do not use the unit without PE connection.
) Unused terminal compartments should be securely tightened.

) Ferrules are allowed.

spring-clamp terminals spring-clamp terminals spring-clamp terminals

2.8mm 2.8mm 2.25mm

24V, 20A, SINGLE PHASE INPUT

Fig. 12-1 Connecting a wire

Daisy Chaining of Outputs:

Daisy chaining (jumping from one power supply output to the next) is allowed as long as the average output current
through one terminal pin does not exceed 25A. If the current is higher, use a separate distribution terminal block as
shown in Fig. 12-3.

Fig. 12-2 Daisy chaining of outputs Fig. 12-3 Using distribution terminals

Sep. 2019 / Rev. 2.3 DS-QS20.241-EN
All parameters are specified at 24V, 20A, 230Vac, 25°C ambient and after a 5 minutes run-in time unless otherwise noted.

11/26

QS20.241, QS20.241-A1, QS20.241-C1

13. F

Overload LED

DC-OK LED

DC-OK Contact

Normal mode

During BonusPower

Overload (

Output short circuit

Temperature Shut

No input power

Q-Series

RONT SIDE AND USER ELEMENTS

Fig. 13-1 Front side

A Input Terminals (Quick-connect spring-clamp terminals)

N, L Line input

B Output Terminals (Quick-connect spring-clamp terminals, two pins

per pole)

+ Positive output
– Negative (return) output

C DC-OK Relay Contact (Quick-connect spring-clamp terminals)

The DC-OK relay contact is synchronized with the DC-OK LED.
See chapter 8 for details.

D Output voltage potentiometer

Open the flap to adjust the output voltage. Factory set: 24.1V

E DC-OK LED (green)

On, when the output voltage is >90% of the adjusted output voltage

24V, 20A, SINGLE PHASE INPUT

PE (Protective Earth) input

F Overload LED (red)

On, when the voltage on the output terminals is <90% of the
adjusted output voltage, or in case of a short circuit in the output.
Input voltage is required.

Indicators, LEDs

OFF ON Closed

®

OFF ON Closed

VOUT < 90%) *) OFF Open

*) OFF Open

-down *) OFF Open

OFF OFF Open

*) Up to 4s of overloading, the power supply delivers continuous output current. After this, the output power is reduced to nearly zero for

approx. 17s before a new start attempt is automatically performed. If the overload has been cleared, the device will operate normally. If the

overload still exists, the output current will be delivered for 2 to 4s (depending on the overload) again followed by a 17s rest time. This cycle

is repeated as long as the overload exists.

The red overload LED is permanently on when the overload current is continuously flowing. During the 17s rest period, the red LED is

flashing with a frequency of approx. 1.3Hz.

Sep. 2019 / Rev. 2.3 DS-QS20.241-EN
All parameters are specified at 24V, 20A, 230Vac, 25°C ambient and after a 5 minutes run-in time unless otherwise noted.

12/26

QS20.241, QS20.241-A1, QS20.241-C1

14. EMC

EMC Immunity

Electrostatic discharge
Electromagnetic RF field

Fast transients (Burst)
Surge voltage on input

EN 61000-4-5

L  N

2kV

Criterion A

Surge voltage on output
Surge voltage on DC

Conducted disturbance

Mains voltage dips

EN 61000-4-11

0% of 100Vac

70% of 200Vac

0Vac, 20ms

140Vac, 500ms

Criterion A

Criterion A

Voltage interruptions

Voltage sags

Powerful transients

EMC Emission

Conducted emission
input lines

Conducted emission
output lines **)

IEC/CISPR 16-1-2, IEC/CISPR 16-2-1

limits for DC power port acc. EN

Radiated emission

Harmonic input current

Voltage fluctuations, flicker

This device complies with FCC Part 15 rules.
Operation is subjected to following two conditions: (1) this device may not cause harmful interference, and (2) this
device

Q-Series

The power supply is suitable for applications in industrial environment as well as in residential, commercial and light
industry environment without any restrictions. A detailed EMC report is available on request.

EN 61000-4-4 input lines

-OK EN 61000-4-5 DC-OK signal  PE 1kV Criterion A
EN 61000-4-6 0.15-80MHz 10V Criterion A

According generic standards: EN 61000-6-1 and EN 61000-6-2
EN 61000-4-2 contact discharge

air discharge

EN 61000-4-3 80MHz-2.7GHz 10V/m Criterion A

output lines
DC-OK signal (coupling clamp)

L  PE, N  PE

EN 61000-4-5 +  -

+ / -  PE

40% of 100Vac
70% of 100Vac
0% of 200Vac
40% of 200Vac

24V, 20A, SINGLE PHASE INPUT

8kV
15kV

4kV
2kV
1kV

4kV
1kV

1kV

40Vac, 200ms
70Vac, 500ms
0Vac, 20ms
80Vac, 200ms

Criterion A
Criterion A

Criterion A
Criterion A
Criterion A

Criterion A
Criterion A

Criterion A

Criterion C
Criterion A
Criterion A
Criterion A

EN 61000-4-11 0% of 200Vac (=0V) 5000ms Criterion C

SEMI F47 0706 dips on the input voltage according to SEMI F47 standard

80% of 120Vac (96Vac)
70% of 120Vac (84Vac)
50% of 120Vac (60Vac)

VDE 0160 over entire load range 750V, 1.3ms Criterion C

Criterions:
A: Power supply shows normal operation behavior within the defined limits.
C: Temporary loss of function is possible. Power supply may shut-down and restarts by itself. No damage or hazards for the power supply

will occur.

EN 55011, EN 55022 Class B

EN 61000-3-2 fulfilled for class A equipment

must accept any interference received, including interference that may cause undesired operation.

*) tested with constant current loads, non pulsing
**) for information only, not mandatory for EN 61000-6-3
***) Quasi-peak values fulfilled, average values +5dB

According generic standards: EN 61000-6-3 and EN 61000-6-4
EN 55011, EN 55022, FCC Part 15, CISPR 11, CISPR 22 Class B

EN 61000-3-3 fulfilled *)

1000ms
500ms
200ms

61000-6-3 not fulfilled ***)

Criterion A
Criterion A
Criterion A

Sep. 2019 / Rev. 2.3 DS-QS20.241-EN
All parameters are specified at 24V, 20A, 230Vac, 25°C ambient and after a 5 minutes run-in time unless otherwise noted.

13/26

QS20.241, QS20.241-A1, QS20.241-C1

Switching

Switching frequency 1

Switching frequency 2

Switching frequency 3

Switching frequency 4

35kHz to 45kHz

Aux. converter, input voltage and load dependent

15. E

Operational temperature

Storage temperature

Outpu

Humidity

Vibration sinusoidal

Shock
Altitude

2000 to 6000m (6 560 to 20 000ft)

reduce output power or ambient temperature,

Altitude de

Over

Degree of pollution

LABS compatibility

Allowed Output
Current at 24V

0

-25 0 20 40

70°C

5

10

15

20

25

30A

continuous

60

Ambient Temperature

for typ. 4s

Allowed Output
Current at 24V

0

0 2000 4000

6000m

5

10

15

20

25

30A

continuous

Altitude

for typ. 4s

A... Tamb < 60°C
B... Tamb < 50°C
C... Tamb < 40°C

A

B

C

24V, 20A, SINGLE PHASE INPUT

Frequencies

Q-Series

The power supply has four converters with four different switching frequencies included.

One is nearly constant. The others are input voltage and load dependent.
100kHz Resonant converter, nearly constant
110kHz to 500kHz Boost converter, input voltage and load dependent
73kHz to 114kHz PFC converter, input voltage and load dependent

NVIRONMENT

*) -25°C to +70°C (-13°F to 158°F) reduce output power according Fig. 15-1

-40 to +85°C (-40°F to 185°F) for storage and transportation

t de-rating 12W/°C 60-70°C (140°F to 158°F)

**) 5 to 95% r.H. IEC 60068-2-30

2-17.8Hz: ±1.6mm; 17.8-500Hz: 2g

2 hours / axis

15g 6ms, 10g 11ms

3 bumps / direction, 18 bumps in total

30g 6ms, 20g 11ms

3 bumps / direction, 18 bumps in total

0 to 2000m (0 to 6 560ft) without any restrictions

IEC 60068-2-6

IEC 60068-2-27, DIN-rail mounting

IEC 60068-2-27, with wall mounting bracket
ZM2.WALL

-rating 30W/1000m or 5°C/1000m > 2000m (6500ft), see Fig. 15-2

-voltage category III IEC 62103, EN 50178, altitudes up to 2000m
II altitudes from 2000m to 6000m

2 IEC 62103, EN 50178, not conductive

The unit does not release any silicone or other LABS-critical substances and is suitable for

use in paint shops.

*) Operational temperature is the same as the ambient temperature and is defined as the air temperature 2cm below the unit.
**) Do not energize while condensation is present

Fig. 15-1 Output current vs. ambient temp. Fig. 15-2 Output current vs. altitude

Sep. 2019 / Rev. 2.3 DS-QS20.241-EN
All parameters are specified at 24V, 20A, 230Vac, 25°C ambient and after a 5 minutes run-in time unless otherwise noted.

see Fig. 15-2
IEC 62103, EN 50178, overvoltage category II

14/26

QS20.241, QS20.241-A1, QS20.241-C1

16. P

Output protection

Output over

Degree of protection

Penetration pr

Over

Input transient protection

Internal input fuse

17. S

Input / output separation

Class of protection

Isolation resistance

PE resistance

Touch current (leakage current)

typ. 0.34mA / 0.93mA

120Vac, 60Hz, TN-,TT-mains / IT-mains

Q-Series

24V, 20A, SINGLE PHASE INPUT

ROTECTION FEATURES

Electronically protected against overload, no-load and short-circuits *)

-voltage protection typ. 32Vdc
max. 37Vdc

IP 20 EN/IEC 60529

otection > 3.5mm / > 5mm top side / bottom side; e.g. screws, small parts

-temperature protection yes Output shut-down with automatic restart
MOV (Metal Oxide Varistor)

included not user replaceable

*) In case of a protection event, audible noise may occur.

In case of an internal power supply defect, a redundant
circuit limits the maximum output voltage. The output
shuts down and automatically attempts to restart.

AFETY FEATURES

*) SELV IEC/EN 60950-1

PELV IEC/EN 60204-1, EN 50178, IEC 62103, IEC 60364-4-41
double or reinforced insulation

I PE (Protective Earth) connection required

> 5MOhm input to output, 500Vdc

< 0.1Ohm

typ. 0.23mA / 0.63mA 100Vac, 50Hz, TN-,TT-mains / IT-mains

typ. 0.58mA / 1.56mA 230Vac, 50Hz, TN-,TT-mains / IT-mains
< 0.31mA / 0.77mA 110Vac, 50Hz, TN-,TT-mains / IT-mains
< 0.45mA / 1.13mA 132Vac, 60Hz, TN-,TT-mains / IT-mains
< 0.80mA / 2.00mA 264Vac, 50Hz, TN-,TT-mains / IT-mains

*) double or reinforced insulation

Sep. 2019 / Rev. 2.3 DS-QS20.241-EN
All parameters are specified at 24V, 20A, 230Vac, 25°C ambient and after a 5 minutes run-in time unless otherwise noted.

15/26

QS20.241, QS20.241-A1, QS20.241-C1

18. D

A D

C

B

B

*)

N

L

Input

DC-ok

Earth, PE

Output

-

+

faults occur.

Q-Series

24V, 20A, SINGLE PHASE INPUT

IELECTRIC STRENGTH

The output voltage is floating and has no ohmic connection to the ground. Type and factory tests are conducted by
the manufacturer. Field tests may be conducted in the field using the appropriate test equipment which applies the
voltage with a slow ramp (2s up and 2s down). Connect all input-terminals together as well as all output poles before
conducting the test. When testing, set the cut-off current settings to the value in the table below.

Fig. 18-1 Dielectric strength

Type test 60s 2500Vac 3000Vac 500Vac 500Vac

Factory test 5s 2500Vac 2500Vac 500Vac 500Vac

Field test 5s 2000Vac 2000Vac 500Vac 500Vac

Cut-off current setting > 15mA > 15mA > 40mA > 1mA

To fulfil the PELV requirements according to EN60204-1 § 6.4.1, we
recommend that either the + pole, the – pole or any other part of
the output circuit shall be connected to the protective earth
system. This helps to avoid situations in which a load starts
unexpectedly or can not be switched off when unnoticed earth

B*) When testing input to DC-OK ensure that the max. voltage between DC-OK and the output is not exceeded (column D). We recommend

connecting DC-OK pins and the output pins together when performing the test.

A B C D

Sep. 2019 / Rev. 2.3 DS-QS20.241-EN
All parameters are specified at 24V, 20A, 230Vac, 25°C ambient and after a 5 minutes run-in time unless otherwise noted.

16/26

QS20.241, QS20.241-A1, QS20.241-C1

19. A

EC Declaration of Conformity

IEC 60950
2

UL 508

IND. CONT. EQ.

Listed for use as Industrial Control Equipment;

E-File: E198865

UL 60950
2

ANSI / ISA 12.12.01
(Class I Div 2)

EN 60079
ATEX
(QS2

Marine

SEMI F47

SEMI F47-0706

GOST P

PPROVALS

nd

nd

-1

Edition

-1

Edition

-15

0.241-A1 only)

Q-Series

The CE mark indicates conformance with the

- EMC directive 2004/108/EC,

- Low-voltage directive (LVD) 2006/95/EC,

- RoHS directive 2011/65/EU and the

- ATEX directive 94/9/EC (only for QS20.241-A1)
CB Scheme,

Information Technology Equipment

U.S.A. (UL 508) and Canada (C22.2 No. 107-1-01);

Recognized for use as Information Technology Equipment,
Level 5; U.S.A. (UL 60950-1) and Canada (C22.2 No. 60950-1);
E-File: E137006
Applicable for altitudes up to 2000m.

-2007

I 3G Ex ec nC II T3 Gc

I

Recognized for use in Hazardous Location Class I Div 2 T3
Groups A,B,C,D systems; U.S.A. (ANSI / ISA 12.12.01-2007) and
Canada (C22.2 No. 213-M1987)

Suitable for use in Class 1 Zone 2 Groups IIa, IIb and IIc
locations. Number of ATEX certificate: EPS 09 ATEX 1 236 X
The power supply must be built-in in an IP54 enclosure.

GL (Germanischer Lloyd) classified and
ABS (American Bureau for Shipping) PDA
Environmental category: C, EMC2
Marine and offshore applications

24V, 20A, SINGLE PHASE INPUT

Ride-through compliance for semiconductor industry.
Full SEMI range compliance
(Input: AC120V or higher, output: < 480W)

Certificate of Conformity for Russia and other GUS countries

Sep. 2019 / Rev. 2.3 DS-QS20.241-EN
All parameters are specified at 24V, 20A, 230Vac, 25°C ambient and after a 5 minutes run-in time unless otherwise noted.

17/26

QS20.241, QS20.241-A1, QS20.241-C1

20. P

W

DIN

Installation Clearances

Q-Series

24V, 20A, SINGLE PHASE INPUT

HYSICAL DIMENSIONS AND WEIGHT

eight 1200g / 2.65lb

-Rail Use 35mm DIN-rails according to EN 60715 or EN 50022 with a height of 7.5 or 15mm.
The DIN-rail height must be added to the unit depth (127mm) to calculate the total required
installation depth.

See chapter 2

Fig. 20-1 Front view Fig. 20-2 Side view

Sep. 2019 / Rev. 2.3 DS-QS20.241-EN
All parameters are specified at 24V, 20A, 230Vac, 25°C ambient and after a 5 minutes run-in time unless otherwise noted.

18/26

QS20.241, QS20.241-A1, QS20.241-C1

21. A

Q-Series

CCESSORIES

21.1. ZM2.WALL WALL MOUNTING BRACKET

This bracket is used to mount the power
supply onto a flat surface without utilizing a DIN-Rail.

24V, 20A, SINGLE PHASE INPUT

21.2. ZM15.SIDE SIDE MOUNTING BRACKET

This bracket is used to mount Dimension units sideways with or without utilizing a DIN-Rail. The two aluminum
brackets and the black plastic slider of the unit have to be detached, so that the steel brackets can be mounted.

For sideway DIN-rail mounting, the removed aluminum brackets and the black plastic slider need to be mounted on
the steel bracket.

Side mounting with DIN-rail brackets Side mounting without DIN-rail brackets

Sep. 2019 / Rev. 2.3 DS-QS20.241-EN
All parameters are specified at 24V, 20A, 230Vac, 25°C ambient and after a 5 minutes run-in time unless otherwise noted.

19/26

QS20.241, QS20.241-A1, QS20.241-C1

24V
20A

Load

L
N

PE

Failure

Monitor

YR40.242

*)

Redundancy
Module

Input1Input

2

Output

+-+

-

+

-

I I

*)

YR40.241

also possible

+ +

- -

QS20.241

Power
Supply

24V,20A

DC­OK

L N PE

+ +

- -

QS20.241

Power
Supply

24V,20A

DC­OK

L N PE

YR40.245

Redundancy

Module

+

-

Input

Output

+

-

YR40.245

Redundancy

Module

+

-

Input

Output

+

-

L
N

PE

I

I

24V
20A

Load

Failure

Monitor

+ +

- -

QS20.241

Power
Supply

24V,20A

DC­OK

L N PE

+ +

- -

QS20.241

Power
Supply

24V,20A

DC­OK

L N PE

Q-Series

21.3. YR40 REDUNDANCY MODULES

YR40.242 – (2x 20A Inputs, 1x 40A output)

The YR40.242 is equipped with two input channels, which are individually decoupled by
utilizing mosfet technology. Using mosfets instead of diodes reduces the heat generation and
the voltage drop between input and output. The YR40.242 does not require an additional
auxiliary voltage and is self-powered even in case of a short circuit across the output.

Due to the low power losses, the unit is very slender and only requires 36mm width on the
DIN-rail.

YR40.245 – (1x 40A input, 1x 40A output)

The YR40.245 is a 40A single channel redundancy module, which is equipped with a plug
connector on the output. The plug connector allows replacing the power supply or the
redundancy module while the system is running. The plug connector avoids that the output
wires can touch and short the load circuit.

The YR40.245 is very slender and only requires 46mm width on the DIN-rail. It also utilizes
mosfet technology instead of diodes for low heat generation and a minimal voltage drop
between input and output. It does not require an additional auxiliary voltage and is self­powered even in case of a short circuit across the output.

24V, 20A, SINGLE PHASE INPUT

Fig. 21-1 Typical 1+1 Redundant configuration

for 20A with a dual redundancy module

Sep. 2019 / Rev. 2.3 DS-QS20.241-EN

Fig. 21-2 Typical N+1 or 1+1 Redundant configuration for 20A with

multiple YR40.245 redundancy modules

All parameters are specified at 24V, 20A, 230Vac, 25°C ambient and after a 5 minutes run-in time unless otherwise noted.

20/26

QS20.241, QS20.241-A1, QS20.241-C1

22. A

100%

P

PEAK

T

PEAK

P

0

T

0

max.

150%

150%100

0

0.2

0.4

0.6

0.8

1.0

DutyCycle

110 120 130 140

P

PEAK

P

0

= 10%

P

0

= 50%

P

0

= 75%

P

0

= 100%

D

uty

C

ycle

T

0

=

T

peak -

(D

utyCycle

x T

peak

)

T

peak + T0

T

peak

D

uty

C

ycle

=

D

uty

C

ycle

T

0

=

T

peak -

(D

utyCycle

x T

peak

)

0.37

1s

- (0.37 x 1s)

= =1.7s

Q-Series

24V, 20A, SINGLE PHASE INPUT

PPLICATION NOTES

22.1. REPETITIVE PULSE LOADING

Typically, a load current is not constant and varies over time. This power supply is designed to support loads with a
higher short-term power demand (=BonusPower
power manager and is available on a repeated basis. If the BonusPower
controller allows it, the output voltage will dip and the next BonusPower
time (see chapter 6) has elapsed.

To avoid this, the following rules must be met:
a) The power demand of the pulse must be below 150% of the nominal output power.
b) The duration of the pulse power must be shorter than the allowed BonusPower
c) The average (R.M.S.) output current must be below the specified continuous output current.

If the R.M.S. current is higher, the unit will respond with a thermal shut-down after a period of time. Use the
maximum duty cycle curve (Fig. 22-2) to check if the average output current is below the nominal current.

Fig. 22-1 Repetitive pulse loads, definitions Fig. 22-2 Max. duty cycle curve

®

). The short-term duration is hardware controlled by an output

®

load lasts longer than the hardware

®

is available after the BonusPower® recovery

®

time. (see output section)

P

Base load (W)

0

P

Pulse load (above 100%)

PEAK

T

Duration between pulses (s)

0

T

Pulse duration (s)

PEAK

Example: A load is powered continuously with 240W (= 50% of the rated output load). From time to time a peak

power of 720W (= 150% of the rated output load) is needed for 1 second.
The question is: How often can this pulse be supplied without overloading the power supply?

- Make a vertical line at P

= 150% and a horizontal line where the vertical line crosses the P0 = 50%

PEAK

curve. Read the max. duty cycle from the duty cycle-axis (= 0.37)

- Calculate the required pause (base load) length T

:

0

- Result: The required pause length = 1.7s

- Max. repetition rate = pulse +pause length = 2.7s

More examples for pulse load compatibility:

P0 T

P

PEAK

T0 P

PEAK

P0 T

PEAK

PEAK

T0
720W 480W 1s >25s 720W 240W 0.1s >0.16s
720W 0W 1s >1.3s 720W 240W 1s >1.6s
600W 240W 1s > 0.75s 720W 240W 3s >4.9s

Sep. 2019 / Rev. 2.3 DS-QS20.241-EN
All parameters are specified at 24V, 20A, 230Vac, 25°C ambient and after a 5 minutes run-in time unless otherwise noted.

21/26

QS20.241, QS20.241-A1, QS20.241-C1

Q-Series

24V, 20A, SINGLE PHASE INPUT

22.2. PEAK CURRENT CAPABILITY

Solenoids, contactors and pneumatic modules often have a steady state coil and a pick-up coil. The inrush current
demand of the pick-up coil is several times higher than the steady-state current and usually exceeds the nominal
output current (including the PowerBoost). The same situation applies when starting a capacitive load.

Branch circuits are often protected with circuit breakers or fuses. In case of a short or an overload in the branch circuit,
the fuse needs a certain amount of over-current to trip or to blow. The peak current capability ensures the safe
operation of subsequent circuit breakers.

Assuming the input voltage is turned on before such an event, the built-in large sized output capacitors inside the
power supply can deliver extra current. Discharging this capacitor causes a voltage dip on the output. The following
two examples show typical voltage dips:

Fig. 22-3 Peak load with 2x the nominal

current for 50ms, typ.

Fig. 22-4 Peak load with 5x the nominal

current for 5ms, typ.

Peak load 40A (resistive) for 50ms
Output voltage dips from 24V to 20V.

Please note: The DC-OK relay triggers when the voltage dips more than 10% for longer than 1ms.

Peak load 100A (resistive) for 5ms
Output voltage dips from 24V to 16V.

22.3. BACK-FEEDING LOADS

Loads such as decelerating motors and inductors can feed voltage back to the power supply. This feature is also called
return voltage immunity or resistance against Back- E.M.F. (Electro Magnetic Force).

This power supply is resistant and does not show malfunctioning when a load feeds back voltage to the power supply.
It does not matter whether the power supply is on or off.

The maximum allowed feed-back-voltage is 34Vdc. The absorbing energy can be calculated according to the built-in
large sized output capacitor which is specified in chapter 6.

22.4. EXTERNAL INPUT PROTECTION

The unit is tested and approved for branch circuits up to 20A. An external protection is only required if the supplying
branch has an ampacity greater than this. Check also local codes and local requirements. In some countries local
regulations might apply.

If an external fuse is necessary or utilized, minimum requirements need to be considered to avoid nuisance tripping of
the circuit breaker. A minimum value of 10A B- or C-Characteristic breaker should be used

Sep. 2019 / Rev. 2.3 DS-QS20.241-EN
All parameters are specified at 24V, 20A, 230Vac, 25°C ambient and after a 5 minutes run-in time unless otherwise noted.

22/26

QS20.241, QS20.241-A1, QS20.241-C1

MCB

Power Supply

AC

DC

+

-

+

-

Load

Wire length

S1... Fault simulation switch

S1

Q-Series

24V, 20A, SINGLE PHASE INPUT

22.5. CHARGING OF BATTERIES

The power supply can be used to charge lead-acid or maintenance free batteries. (Two 12V batteries in series)

Instructions for charging batteries:

a) Set output voltage (measured at no load and at the battery end of the cable) very precisely to the end-of-charge

voltage.

End-of-charge voltage 27.8V 27.5V 27.15V 26.8V

Battery temperature 10°C 20°C 30°C 40°C

b) Use a 30A or 32A circuit breaker (or blocking diode) between the power supply and the battery.
c) Ensure that the output current of the power supply is below the allowed charging current of the battery.
d) Use only matched batteries when putting 12V types in series.
e) The return current to the power supply (battery discharge current) is typ. 9mA when the power supply is switched

off (except in case a blocking diode is utilized).

22.6. OUTPUT CIRCUIT BREAKERS

Standard miniature circuit breakers (MCB’s or UL1077 circuit breakers) are commonly used for AC-supply systems and
may also be used on 24V branches.

MCB’s are designed to protect wires and circuits. If the ampere value and the characteristics of the MCB are adapted to
the wire size that is used, the wiring is considered as thermally safe regardless of whether the MCB opens or not.

To avoid voltage dips and under-voltage situations in adjacent 24V branches which are supplied by the same source, a
fast (magnetic) tripping of the MCB is desired. A quick shutdown within 10ms is necessary corresponding roughly to
the ride-through time of PLC's. This requires power supplies with high current reserves and large output capacitors.
Furthermore, the impedance of the faulty branch must be sufficiently small in order for the current to actually flow.
The best current reserve in the power supply does not help if Ohm’s law does not permit current flow. The following
table has typical test results showing which B- and C-Characteristic MCBs magnetically trip depending on the wire cross
section and wire length.

Fig. 22-5 Test circuit

Maximal wire length

0.75mm² 1.0mm² 1.5mm² 2.5mm²
C-2A
C-3A
C-4A
C-6A
C-8A
C-10A
C-13A
B-6A
B-10A
B-13A

*)

for a fast (magnetic) tripping:

26m 35m 62m 82m
23m 29m 54m 72m
15m 19m 31m 51m

7m 10m 15m 26m
5m 7m 10m 16m
2m 3m 5m 7m

- - 1m 2m

19m 27m 38m 57m

7m 11m 14m 23m
1m 2m 3m 5m

*) Don’t forget to consider twice the distance to the load (or cable length) when calculating the total wire length (+ and – wire).

Sep. 2019 / Rev. 2.3 DS-QS20.241-EN
All parameters are specified at 24V, 20A, 230Vac, 25°C ambient and after a 5 minutes run-in time unless otherwise noted.

23/26

QS20.241, QS20.241-A1, QS20.241-C1

Unit A

AC

DC

Unit B

AC

DC

-

+

-

+

Load

+

-

24V

20A

Load

L
N

PE

Failure

Monitor

YR40.242

*)

Redundancy
Module

Input1Input

2

Output

+-+

-

+

-

I I

*)

YR40.241

also possible

+ +

- -

QS20.241

Power
Supply

24V,20A

DC­OK

L N PE

+ +

- -

QS20.241

Power
Supply

24V,20A

DC­OK

L N PE

Q-Series

24V, 20A, SINGLE PHASE INPUT

22.7. PARALLEL USE TO INCREASE OUTPUT POWER

Power supplies from the same series (Q-Series) can be paralleled to increase
the output power. The output voltage shall be adjusted to the same value
(±100mV) with the same load conditions on all units, or the units can be left
with the factory settings.

If more than three units are connected in parallel, a fuse or circuit breaker
with a rating of 30A or 32A is required on each output. Alternatively, a diode
or redundancy module can also be utilized.

Keep an installation clearance of 15mm (left / right) between two power
supplies and avoid installing the power supplies on top of each other. Do not
use power supplies in parallel in mounting orientations other than the standard mounting orientation (input terminals
on bottom and output terminals on the top of the unit) or in any other condition where a derating of the output
current is required (e.g. altitude, above 60°C, …).

Pay attention that leakage current, EMI, inrush current, harmonics will increase when using multiple power supplies.

22.8. PARALLEL USE FOR REDUNDANCY

Power supplies can be paralleled for redundancy to gain higher system availability. Redundant systems require a
certain amount of extra power to support the load in case one power supply unit fails. The simplest way is to put two
power supplies in parallel. This is called a 1+1 redundancy. In case one power supply unit fails, the other one is
automatically able to support the load current without any interruption.
Redundant systems for a higher power demand are usually built in a
N+1 method. E.g. five power supplies, each rated for 20A are paralleled
to build a 80A redundant system. For N+1 redundancy the same
restrictions apply as for increasing the output power, see also section

22.7.

Please note: This simple way to build a redundant system does not
cover failures such as an internal short circuit in the secondary side of
the power supply. In such a case, the defective unit becomes a load for
the other power supplies and the output voltage can not be maintained
any more. This can be avoided by utilizing decoupling diodes or Mosfets,
which are included in the redundancy module YR40.241 or YR40.242.

Recommendations for building redundant power systems:

a) Use separate input fuses for each power supply.
b) Monitor the individual power supply units. Therefore, use the DC-

OK relay contact of the QS20 power supply.

c) It is desirable to set the output voltages of all units to the same

value (± 100mV) or leave it at the factory setting.

Sep. 2019 / Rev. 2.3 DS-QS20.241-EN
All parameters are specified at 24V, 20A, 230Vac, 25°C ambient and after a 5 minutes run-in time unless otherwise noted.

24/26

QS20.241, QS20.241-A1, QS20.241-C1

Unit A

AC

DC

Unit B

AC

DC

-

+

-

+

Load

+

-

Earth
(see notes)

240V

+15%

max.

Fuse

L2

L1

L3

L

N

PE

Power Supply

AC

DC

internal

fuse

Q-Series

24V, 20A, SINGLE PHASE INPUT

22.9. SERIES OPERATION

Power supplies of the same type can be connected in series for higher
output voltages. It is possible to connect as many units in series as needed,
providing the sum of the output voltage does not exceed 150Vdc. Voltages
with a potential above 60Vdc are not SELV any more and can be dangerous.
Such voltages must be installed with a protection against touching.

Earthing of the output is required when the sum of the output voltage is
above 60Vdc.

Avoid return voltage (e.g. from a decelerating motor or battery) which is
applied to the output terminals.

Keep an installation clearance of 15mm (left / right) between two power supplies and avoid installing the power
supplies on top of each other. Do not use power supplies in series in mounting orientations other than the standard
mounting orientation (input terminals on bottom and output terminals on the top of the unit).

Pay attention that leakage current, EMI, inrush current, harmonics will increase when using multiple power supplies.

22.10. INDUCTIVE AND CAPACITIVE LOADS

The unit is designed to supply any kind of loads, including unlimited capacitive and inductive loads.

22.11. OPERATION ON TWO PHASES

The power supply can also be used on two-phases of a three-phase-system.
Such a phase-to-phase connection is allowed as long as the supplying
voltage is below 240V

+15%

. Use a fuse or a circuit breaker to protect the N
input. The N input is internally not protected and is in this case connected to
a hot wire. Appropriate fuses or circuit breakers are specified in section 22.4
“External Input Protection”.

22.12. USE IN A TIGHTLY SEALED ENCLOSURE

When the power supply is installed in a tightly sealed enclosure, the temperature inside the enclosure will be higher
than outside. In such situations, the inside temperature defines the ambient temperature for the power supply.

The following measurement results can be used as a reference to estimate the temperature rise inside the enclosure.
The power supply is placed in the middle of the box, no other heat producing items are inside the box
Enclosure: Rittal Typ IP66 Box PK 9522 100, plastic, 254x180x165mm

Load: 24V, 16A; (=80%) load is placed outside the box
Input: 230Vac
Temperature inside enclosure: 49.2°C (in the middle of the right side of the power supply with a distance of 2cm)
Temperature outside enclosure: 24.4°C
Temperature rise: 24.8K

Sep. 2019 / Rev. 2.3 DS-QS20.241-EN
All parameters are specified at 24V, 20A, 230Vac, 25°C ambient and after a 5 minutes run-in time unless otherwise noted.

25/26

QS20.241, QS20.241-A1, QS20.241-C1

Power

Supply

OUTPUT

INPUT

Output Current

0

10 20 30 40

60°C

4

12

16

20A

50

A1

8

Ambient Temperature

Power

Supply

OUTPUT

INPUT

Output Current

0

10 20 30 40

60°C

4

12

16

20A

50

8

Ambient Temperature

A1

A2

Output Current

0

10 20 30 40

60°C

4

12

16

20A

50

8

Ambient Temperature

A1

A2

Power

Supply

OUTPUT

INPUT

Output Current

0

10 20 30 40

60°C

4

12

16

20A

50

8

Ambient Temperature

A1

A2

Power

Supply

OUTPUT

INPUT

Output Current

0

10 20 30 40

60°C

4

12

16

20A

50

8

Ambient Temperature

A1

A2

Q-Series

24V, 20A, SINGLE PHASE INPUT

22.13. MOUNTING ORIENTATIONS

Mounting orientations other than input terminals on the bottom and output on the top require a reduction in
continuous output power or a limitation in the maximum allowed ambient temperature. The amount of reduction
influences the lifetime expectancy of the power supply. Therefore, two different derating curves for continuous
operation can be found below:

Curve A1 Recommended output current.
Curve A2 Max allowed output current (results in approximately half the lifetime expectancy of A1).

Fig. 22-6
Mounting
Orientation A

(Standard
orientation)

Fig. 22-7

Mounting
Orientation B

(Upside down)

Fig. 22-8

Mounting
Orientation C

(Table-top
mounting)

Fig. 22-9

Mounting
Orientation D

(Horizontal cw)

Fig. 22-10

Mounting
Orientation E

(Horizontal ccw)

Sep. 2019 / Rev. 2.3 DS-QS20.241-EN
All parameters are specified at 24V, 20A, 230Vac, 25°C ambient and after a 5 minutes run-in time unless otherwise noted.

26/26