PSS1250-HS-3-D G.M. International s.r.l.
GM International

SIL 3 Power Supply System, 24Vdc, 50A redundant, Zone 2 / Div. 2

The Power Supply System type PSS1250 is an anodized aluminum 9" Rack unit (4U high) suitable to accept up to 2 plug-in Power Supply Modules type PSM1250 and 1 Overview module for diagnostic functions (modules are NOT included in this ordering code). Each module is able to provide 24Vdc, 50 A output. Modules can be paralleled with load sharing circuits which distribute current load equally to each power supply module to increase reliability and reduce internal power dissipation. The system accepts up to two independent AC power sources from 110 to 240 Vac (+/- 10%).


  • SIL 3 for NE Load according IEC 61508:2010, with single PSM1250 module or two PSM1250 modules in redundant configuration.
  • SIL 2 for ND Load according IEC 61508:2010, with two PSM1250 modules in redundant configuration.
  • 2 universal AC Input Lines, 110 to 240 Vac (+/- 10%) (48 to 62 Hz).
  • Power factor correction.
  • Installation in Zone 2 / Div. 2 hazardous locations with hot swappable modules.
  • EMC Compatibility to EN61000-6-2, EN61000-6-4.
  • ATEX, IECEx, UL & C-UL, TÜV Certifications.
  • TÜV Functional Safety Certification.
  • Highly regulated output of 24 Vdc (21÷28 Vdc setting range), 50 A, for PSM1250 module.
  • 1 x redundant system output 24 Vdc, 50 A.
  • Under and over voltage alarm monitoring.
  • 3 over voltage redundant protections.
  • Redundant parallel connections with load sharing.
  • Reduces Power dissipation (in parallel/redundant configuration) by replacing a Schottky diode with Mosfet Active Ideal Diode.
  • 89% efficiency @230 Vac input and 24 Vdc output with full load.
  • Fan speed control depending on ambient temperature and output power.
  • High load fuse breaking capability without interrupting operations.
  • Wall mounted 9" Rack unit, 4 U high, anodized aluminium, durable metal enclosure.
  • Tropicalization for electronic components.
  • Modbus RTU RS-485 diagnostic output.


Product lifecycle policy (EN)

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Technical Data


AC Input voltage nominal 110 to 240 Vac (±10%), with frequency range 48 to 62 Hz.
Power Factor Correction (AC input) 0.98 typ.@230Vac, 0.995 typ.@115Vac full load (for each PSM1250 module).
Efficiency @24Vdc out (full load) better than 89 % @ 230 Vac and 86% @ 115 Vac (for each PSM1250 module).
Max. internal power dissipation @24Vdc out (full load) 150 W @ 230 Vac; 195 W @ 115 Vac (for each PSM1250 module).
AC input current (sinusoidal at full load) @24Vdc out 14.2A @100Vac input voltage, 12.2 A @115 Vac input voltage, 6.1 A @230 Vac input voltage (for each PSM1250 module).
Inrush current 37 A peak @ 264 Vac; 32 A peak @ 230 Vac; 16 A peak @ 115 Vac (for each PSM1250 module).
AC input connection screw terminal blocks suitable for 4mm2 wires on back panel pcb.


Input to Output isolation 2500 Vrms (routine test).
Input to Earth-Ground isolation 1500 Vrms (routine test).
Earth-Ground to Output isolation 500 Vrms (routine test).
Output or Earth-Ground to Fault contact isolation 500 Vrms (routine test)


Voltage 24 Vdc (adjustable from 21 to 28 Vdc).
Regulation 0.4 % for a 100 % load change.
Stability 0.01 % for a 20 % line voltage change.
Ripple ≤ 250 mVpp.
Output current 50 A nominal (@24Vdc out) (for each PSM1250 module). Parallel connection for redundancy with load sharing capability within ±5 % of output voltage setting.
Output power up to 1300 W nominal (@28Vdc out) (for each PSM1250 module).
Output Rise Time 2.5 s.
Dynamic Response 2 ms for 0-100% load change (overshoot ±1.5% of Vout setting).
Connection M6 screw terminals on copper bars suitable for lug (at least 6.5 mm hole diameter) with 16mm2 wire on back panel pcb.
Hold-up time at full load 20 ms (AC input) (for each PSM1250 module).
Over voltage protection output limited to 30 Vdc plus two redundant crowbars for over voltage protection at 30 Vdc (for each PSM1250 module).

Power good signaling

Output good 19.5 V ≤ Vout ≤ 29.5 V.
Indication via LCD screen on PSO1250 and Modbus RTU RS-485 protocol.
Signaling voltage free SPST normally energized relay (contact closed), de-energize in over/under voltage conditions (contact open) (for each PSM1250 module).
Contact rating 2 A 50 Vac 100 VA, 2 A 24 Vdc 48 W (resistive load).
Connection screw terminal blocks suitable for 1.5 mm2 wires on back panel pcb.

Environmental conditions

Operating temperature limits -40 to +70°C de-rated linearly 65-70% load above 50°C.
Relative humidity limits 95 %, up to 55 °C.
Transport, storage temperature limits - 45 to + 85 °C.
Max altitude 2000 m a.s.l.


Mounting 7” or 9” or 19” Rack unit, 4 units high. 7” or 9” Rack unit for wall mounting, into a cabinet. 19” Rack unit for wall mounting or for frontal rack mounting, into a cabinet.
Weight 7” fully equipped about 7 Kg, fully equipped with 2 PSM1250. 9” fully equipped about 10 Kg, fully equipped with 2 PSM1250 and 1 PSO1250 module. 19” fully equipped about 24 Kg, fully equipped with 6 PSM1250 and 1 PSO1250 module.
Location installation in Safe Area/Non Hazardous Locations or Zone 2, Group IIC T4 or Class I, Division 2, Group A,B,C,D, T4.
Protection class IP 20, Open Type.
Dimensions Width 482 mm, Depth 360 mm, Height 237.30 mm (PSS1250-HS-7-1/2/3/4-D & PSS1250-7-1/2/3/4-D) . Width 442.20 mm, Depth 368.88 mm, Height 242 mm (PSS1250-HS-7-6/7/8/9-D & PSS1250-7-6/7/8/9-D) . Width 238 mm, Depth 360 mm, Height 237.30 mm (PSS1250-HS-3-D & PSS1250-3-D). Width 178 mm, Depth 360 mm, Height 237.30 mm (PSS1250-HS-2 & PSS1250-2).

Data Sheet

Datasheet of PSS1250 ( EN )

Instruction Manual

Instruction Manual PSS1250 ( EN )
Ex safety instruction manual for PSx1200 series ( EN | IT )
CCC Ex safety instruction manual for PSx1200 series ( EN | CN )


Type Description Area Number Issued by Issue Date
ATEX DEKRA ATEX PSS1250, PSW1250, PSW1230 Series English Certificate ( EN ) Europe BVS 15 ATEX E 006 X DEKRA 2022-08-01
Ex PSx1200 CCC certificate for China ( EN ) China 2020322303000822 NEPSI 2023-04-30
Ex UL-cUL PSW1250, PSS1250 Hazardous ( EN ) North America 20190530-E498342 UL 2019-05-30
FSM TUV IT 22 SIL 0093 Functional Safety Certificate ( EN ) International TUV IT 22 SIL 0093 TUV_SUD 2022-07-25
IECEx DEKRA IECEx PSS1250, PSW1250, PSW1230 Series Certificate ( EN ) International IECEx BVS 15.0006X DEKRA 2022-09-08
SIL TUV C-IS-236198-04 SIL Certificate Summary ( EN ) International C-IS-236198-04 TUV_SUD 2022-10-14

Declarations of Conformity

EU Declaration of Conformity for PSS1250, PSW1250, PSW1230 ( EN | IT )
EU Declaration of Conformity for RoHS, ASBESTOS. ( EN )
Declaration of G3 compliance for D1000_PSD1000-PSD1001-PSD1001C-PSD1004-PSD1220-PSD1220-098 SERIES ( EN )