3 Phase Static Transfer Switch Specifications And Data

Name: 3 Phase Static Transfer Switch
Brand: Nepson Industrial

Product Overview

What This Unit Does

The STS is built with two independent power inlets. The load normally runs from the primary source. If the primary source fails, the secondary source picks the load up automatically and the transfer is seamless to the connected equipment. Once the primary input is restored the switch returns the load to it. Standard ratings run from 63 A to 400 A per phase at 3 phase 380 V.

Key Benefits

Transfer time of 6 ms or less, short enough that servers and controllers do not reboot
Two separately independent sources give real redundancy, not a shared bus
Automatic return to the priority source removes a manual step after a fault
Efficiency of 98 percent or better keeps heat and running cost down
LCD shows voltage, current and power, LED shows working status at a glance

Problems It Solves

One feed fails and the whole rack drops out
Mechanical changeover gear is too slow and the load still sees an interruption
After a fault the load stays on the backup feed until somebody remembers to switch back

Application Scenarios

Dual feed server rooms and network closets
Redundant supply to PLC, DCS and instrument cabinets
Feeding a UPS bank from two utility transformers
Broadcast and telecom equipment rooms

Who It Is For

Data centre operators
Telecom and broadcast facilities
Plant electrical engineers
Building services contractors

Technical Features

How It Is Built

Two independent 3 phase inlets with source A as priority
SCR switching with first disconnect then connect sequencing
3 pole transfer, optional 3 pole plus neutral
MCB or moulded case circuit breaker per rating
Air cooling with AC fans that start on over temperature
LCD metering of voltage, current and power

Specifications

Published Data

Every figure below comes from the manufacturer data for this model family.

Models	HPS-3363, HPS-33100, HPS-33160, HPS-33250, HPS-33300, HPS-33400
Input Phases	3 phase
Input Voltage	AC 380 V plus or minus 15 percent, other voltages customised
Input Frequency	50 or 60 Hz
Output Voltage	AC 380 V plus or minus 15 percent, 3 phase
Max Current Per Phase	63 A, 100 A, 160 A, 250 A, 300 A, 400 A
Connectors	Terminal block
Breaker	MCB or moulded case circuit breaker
Transfer Time	6 ms or less typical
Transfer Poles	3P, optional 3P plus N
Priority	Input source A
Transfer Type	SCR, first disconnect then connect
Efficiency	98 percent or better
Cooling	Air cooling, AC fan starts on over temperature
Insulation Resistance	DC 500 V, 20 megohm or more
Withstand Voltage	AC 1800 V, 10 mA for 1 minute
Operating Temperature	0 to 45 degrees C
Relative Humidity	0 to 99 percent non condensing
Operating Altitude	1500 m or less
Dimensions	600 x 600 x 1000 mm or 600 x 800 x 1760 mm depending on rating
Net Weight	65, 70, 80, 105, 155 and 215 kg by rating

Manufacturing Process

From Cabinet To Tested Unit

Sheet metal cabinet build

SCR power assembly and busbar work

Control and metering wiring

Transfer timing test on both sources

Quality Control

Insulation resistance measured at DC 500 V
Withstand voltage held at AC 1800 V for one minute
Transfer sequence exercised on both inlets before shipment

Certifications

CE
RoHS

Customisation Options

Input and output voltage other than 380 V on request
3 pole plus neutral switching
Breaker type matched to the upstream protection on site

Comparison

Against The Alternatives

Mechanical automatic transfer switch	A mechanical ATS takes tens or hundreds of milliseconds. The STS transfers in 6 ms or less, so IT loads ride through without a restart.
Adding a second UPS	A second UPS duplicates batteries and service cost. The STS gives source redundancy ahead of the UPS at a fraction of the footprint.

Use Guide

Getting It Right On Site

Feed the two inlets from genuinely independent transformers or feeders
Keep source A as the priority feed so return transfer is predictable
Size the rating on the actual per phase current, not on the cabinet size
Keep the operating area below 45 degrees C and 1500 m altitude, or derate

FAQ

Questions Buyers Ask

Will my servers reboot during a transfer?

Typical transfer time is 6 ms or less, which is inside the ride through window of a normal switch mode power supply, so connected equipment keeps running.

Does it switch the neutral?

Standard transfer is 3 pole. A 3 pole plus neutral version is available as an option.

What is the largest model?

HPS-33400 at 400 A per phase, in a 600 x 800 x 1760 mm cabinet weighing 215 kg.

How much power does the switch itself consume?

Efficiency is 98 percent or better, so losses stay low and the cabinet is air cooled.

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