Helios SR750HL 750W Power Supply/Float Charger User's Manual

Introduction

The SR750HL range is designed for use as a reliable and stable AC to DC power supply, or float charger for lead acid batteries. For float charging, the output voltage must be set to approximately 15% above the nominal battery voltage. This is the default for the 12V model but must be specified at the time of order for higher voltage models.

Standard Features

• [relay] 3 Relay Alarms - Form C

  Describes relay contacts shown in a de-energised state, indicating a fault condition. Alarm relays energise when the power supply is operating normally.

  • DC HIGH: DC Output High.
  • POWER: Loss of mains input power (30-second delay).
  • DC LOW: DC Output Low or Battery voltage low.
  • Fan Fail/Stall: Indicates one or both fans are stalled or failed. This triggers a slow flashing of the POWER OK LED and the DC HIGH alarm relay toggles every 5 seconds.

• [float charger] Float Charger - Lead Acid Batteries

Optional Features

• Comms:

  • RS232
  • RS485
  • Modbus RTU
  • SNMP V1 & Webpages

• [I/O] Customizable Digital I/O

  Digital Inputs (pins 1,2) / Input or Output (pin 3) / Return (pin 4) terminals are customizable.

• [temp sensor] Temperature Sensor on 1.7m lead with adhesive pad: -4mV/°C/cell ±10%

• [redundancy] N+1 Redundancy

• [rack mount] Rack Mounting

• [meter] Internal Meter

Front & Back Panel Layout

The front panel includes:

• 1. AC INPUT: IEC60320 - C13 10A socket.
• 2. Digital Inputs/I/O Terminals: Customizable terminals for digital inputs or outputs.
• 3. ALARMS RELAY FORM C: Relay contacts for fault conditions.
• 4. DC CONNECTIONS: Options include M8 brass stud, plug-in style phoenix socket & mating screw terminal, and plug-in style Anderson connector. For loads exceeding 20A, both terminals per polarity must be used.

The rear panel features various connection points for AC input, DC output, and communication ports.

LED Indications Code

Indicates the operational status of the unit:

LEGEND: ☀️ = On, 〰️ = slow flash, ⚡ = fast flash, ⚪ = Off.

Alarm Terminal Layout

Relay contacts shown in de-energised state (i.e., when there is a fault condition). Alarm relays are energised when the power supply is operating normally. DC OK alarm indicates either DC low or DC high.

Comms Ports

Supports various communication protocols:

• RS232 (ASCII): https://www.heliosps.com/sr-series-downloads/#rs232-rs485-commands-sr-series
• RS485 (ASCII): https://www.heliosps.com/sr-series-downloads/#rs232-rs485-commands-sr-series
• Modbus RTU: https://www.heliosps.com/sr-series-downloads/#serial-modbus-rtu-sr-series
• SNMP, Webpages: https://www.heliosps.com/sr-series-downloads/#snmp-sr-series

Note: A battery is required for communications to continue working in the event of an input/internal converter failure.

Frame Ground (FG)

This terminal provides a connection to the metal case for earthing.

Model Coding and Options

The model number structure defines various configurations:

Example: SR750HL 12 T F X L DC 485+

N+1 Redundancy

An external diode is required for N+1 redundancy or parallel applications. A diode and DC Power Supply can be installed in a 2U Rack. Contact Helios technical engineers for configuration assistance.

[Diagram Description: Image shows a Helios SR500-750HL unit with an external diode installed in a 2U Rack.]

Connection Notes

• Models with screw/unpluggable connectors have two terminals per polarity, each rated at 20A. Both terminals must be used if the load current exceeds 20A.
• When used as a battery charger, ensure the battery polarity matches the power supply/charging output.
• Alarms can be tested using an external variable voltage supply.

Technical Specifications

Options

• Optional Input Voltage: 88-132 VAC
• Optional DC Input Voltage: 110VDC (88V - 135VDC) - Requires external fuse or MCB on output for short circuit protection.
• Communication Port: RS232 (ASCII), RS485 (ASCII), Modbus RTU, SNMP, Webpages
• Digital Inputs/Outputs: Digital Input (pins 1,2) / Input or Output (pin 3) / Return (pin 4)
• Temp. Compensation: Temperature sensor on 1.7m lead with adhesive pad: -4mV / °C / cell ±10%
• Internal Meter: Internal V/I meter displaying PSU operating states and analogue.
• Mounting: Standalone, 19" Rack Mount - Optional V/I meter for subrack: SR-Meter
• N+1 Redundancy: Using 2 chargers each with its own battery & output diodes.
• Conformal Coating: For harsh environments.

H-Series Internal Meter Option

SR500H & SR750HL & I models feature an internal meter. The displayed parameters vary by model.

[Diagram Description: Example display for H-Series internal meter.]

Code A:

• CC - charge cycle (normal operation)
• MF - mains fail (mains failure, system on battery power)
• OL - system overloaded, output voltage is below Vpres setting

Code B:

• M? - possible mains fail (no mains detected but brown out timer not expired, 30sec)
• BP - System OK
• BM - DC Low alarm
• BL - DC High alarm

Displayed values following Code B:

• Vout = output voltage of PSU
• Ibat = 0 for HL models (2 terminal DC Power Supply)
• Ipsu = Total PSU output current
• +20°C = temperature measured by temp. sensor

Customised Models

Terms of Warranty

Helios Power Solutions warrants this product for 24 months from date of shipment against material and workmanship defects. Liability under this warranty is limited to the replacement or repair of the defective product, provided the product has not been damaged through misapplication, negligence, or unauthorized modification or repair.

Safety Information

Users are responsible for ensuring input and output wiring segregation complies with local standards and that access is confined to operators and service personnel. A low resistance earth connection is essential for safety and satisfactory EMI suppression.

HAZARDOUS VOLTAGES EXIST WITHIN A POWER SUPPLY ENCLOSURE AND ANY REPAIRS MUST BE CARRIED OUT BY A QUALIFIED SERVICEPERSON.

Electrical Strength Tests

Components are constructed to provide electrical isolation as required by relevant standards. However, EMI filtering components may be damaged by excessively long high voltage tests between input, output, and ground. Contact Helios technicians for advice.

Earth Leakage

EMC suppression circuits may cause earth leakage currents up to a maximum of 3.5mA.

Ventilation

High operating temperatures reduce component life. Ensure adequate ventilation. Batteries are particularly susceptible to shortened lifetimes in high ambient temperatures.

Water / Dust

Minimize the risk of water or dust ingress. Water can cause instant failure. Dust effects are slower but all electrical equipment should be cleaned regularly.

Electromagnetic Interference (EMI)

Switching power supplies generate electrical noise. Wiring should be short and segregated from sensitive equipment. Ferrite cores can reduce residual noise by looping DC wiring through them.

External Fuse Protection

Fuses or circuit breakers must be used in all battery circuits for short circuit protection. External fuses are recommended for power supplies/chargers even if internally protected.

Connection Polarity

It is critical to check polarity carefully when connecting DC devices, even those with reverse polarity protection.

Glossary of Terms

• PSU = power supply unit
• ELVD = electronic low voltage disconnect
• SNMP = Simple Network Management Protocol
• BCT = battery condition test
• RPP = reverse polarity protection
• EMC = Electromagnetic compatibility
• ECB = electronic circuit breaker
• EMI = electromagnetic interference
• DOD = depth of discharge