DM-1000

The DM-1000 ETU replaces the Masterpact M OEM’s inherently faulty STR type trip units which, unfortunately, often suffer from non-repairable, spurious tripping problems. The DM-1000 is form-fit manufactured to make retro-fitting the trip unit device as easy and as fast as possible and utilises the existing current sensor connections of the Masterpact Air Circuit Breaker (ACB).

This UK designed and manufactured unit uses British electrical switchgear design practices and philosophy and gives high priority to safety, reliability and performance. Key to the design process was the management decision at the start to build high safety margins into the design, and utilise only industrial grade electronic components from reliable suppliers in the UK / EU / North America, including high life AL EL capacitors with additional derating to give a life expectancy of > 40 years.

The DM-1000 can be programmed to model any of the five original manufacturer’s STR type trip units* found on the Masterpact M ACB, such as the STR18I, STR18M, STR28D, STR38S & STR58U giving you the same settings and options available on each model as the original, making the replacement of an existing STR type trip unit an easy task without need for setting recalculation or a costly protection study. If you want something different, the DM-1000 can also be programmed to utilise any combination of the settings and options available, making this a very versatile protection unit, which can be used on any Masterpact M frame (08 – 63), any CT rating (200 – 6300A), any breaking capacity type (N1 / H1 / H2 / L1), poles (3 or 4), fixed or drawout construction, and frequency (50 / 60Hz) system without requirement for changing of rating plugs.

With class leading innovative internal power management & efficiency the DM-1000 is fully functional (monitor, measure, display and trip) from as little as 8% single phase load – and a mere 2% three phase load – without need for external 24VDC supply – making it a clear leader amongst the competition. The main benefits of this are that the User can see what current is flowing at far lower values than on other units – as well as being able to set the Ground Fault trip setting down to its lowest setting (0.1 x Ir) and it be able to function without an external 24VDC power supply being used.

In addition the large 21 character x 8 row backlit LCD display shows all four phase currents with their percentage of Ir, and when in overload, the Thermal Content % – as well as date & time, battery status, the ACB’s main characteristics, Long Time (LT) pickup value, Trip Unit “modelled”, and all the protective functions and options’ ON / OFF status’.

If a fault trip is experienced, the unit displays a time-stamped trip screen with details of the protection band tripped on, and all the phase current values at point of tripping. In fact, the DM-1000 can store hundreds of time-stamped events in its logs covering fault trips, test trips, cascaded setting changes, and servicing.

* Using standard Current Sensors. This excludes the different sensors used on the STR68U which are not compatible with the DM-1000

Each of the five modelled “STR” types contain all the protection functions, settings and options available to the original units so that the functionality and settings of the unit being replaced can be matched completely.

Available within the firmware (dependent on modelled unit selected) and hardware design are the following protection types:  

Trip Units Modelled:                                       DM18I / DM18M / DM28D / DM38S / DM58U

Long Time Protection Settings (Programmable)
LT Pick Up 0.4 to 1.0 x In
LT Time Delay 15 – 480s

Short Time Protection Settings (Programmable)
ST Pick Up 1.5 to 10.0 x Ir
ST Time Delay 0.1 to 0.4s + I2t

Instantaneous Protection Settings (Programmable)
INST Pick Up 1.5 to 28.0 x In

Ground Fault Protection Settings (Programmable)
GF Pick Up 0.1 to 1.0 x Ir (or 1200A max)
GF Time Delay 0.1 to 0.4s + I2t

Phase Imbalance Protection Settings (Programmable)
PI Pick Up 0.25 to 0.70 x Ir
PI Time Delay 1 to 90s

Making Current Release / DINF Protection (Hardware based via dip switches on installation)
MCR Pick Up Set to breaker parameters

High Set Instantaneous Protection (Hardware based via dip switches on installation)
HSI Pick Up Set to breaker parameters