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STAMFORD DM110 Digital Automatic Voltage Regulator (AVR)

Description

Digital excitation control for paralleled and grid-connected sets

The STAMFORD DM110 is a microprocessor-based digital AVR developed by Cummins Generator Technologies with Basler Electric, who produce it for STAMFORD and AvK products. It controls the output of brushless synchronous generators up to 5 MW through a 7 A dc pulse-width-modulated power stage, and is described as ideal for machines paralleled to other generators or the utility, and for distributed generation, co-generation and peak-shaving duty.

The sensing input accepts nominal voltage up to 600 V ac with no potential transformer, adjustable in 0.1 V steps so circulating current between paralleled sets is not a problem. Regulation on the generator is 0.5 percent. Set-up, adjustment and monitoring are done from a PC through the supplied BESTCOMS software on the front RS-232 port.

Technical specifications

Parameter Specification
Type Microprocessor-based digital AVR, produced by Basler Electric for STAMFORD-AvK
Output stage 63 V dc at 7 A dc, PWM
Regulation 0.5% on the generator
Sensing Up to 600 V ac, 0.1 V adjustment steps, no PT required
Machine size Brushless synchronous generators up to 5 MW
Stability 20 standard selections plus one customisable
Limiting 0-3 x V/Hz; over-excitation (summing point or takeover); under-excitation
Control modes Voltage, VAR/PF, manual (field current regulation)
Protection functions Five, including over-excitation shutdown, generator over-voltage, loss of sensing (transfer to manual), field over-voltage
Paralleling input From 1 A or 5 A CT
Remote control Built-in 4-20 mA interface
Motor start 2 selectable motor start programs
Communications RS-232 DB9, BESTCOMS software on CD
Size W 135.6 x H 74.8 x D 72.1 mm (horizontal footprint)
Approvals cURus recognition per UL 508 and CSA C22.2 No. 14; CE compliant; DNV certified

Where it is fitted

The bulletin lists the DM110 as available on LVI P80, MVI P80, HVI P80, DSG and DIG alternators and their marine equivalents. In the S-Range it appears as the standard AVR on the S9LV and as an option on the S6 and S7K.

Functions that replace external devices

Integrated VAR/PF control saves buying remote devices for utility-paralleled sets. Voltage matching lets a less expensive synchronising device be used. Softstart limits voltage overshoot at build-up, and the dwell function delays voltage recovery after a dip so engine speed can recover first. Nine front-panel LEDs show generator system and DM110 conditions without a PC, and a fail-safe alarm closes on loss of power.

Choosing between STAMFORD regulators

The DM110 is the digital choice; analogue AVRs below are sensed by simpler means.

AVR Excitation power Sensing Max. continuous output Regulation
SX460 From generator terminals 95-132 or 190-264 V ac, 1 phase 4 A dc +/-1.0%
AS440 From stator or auxiliary winding 100-130 or 190-264 V ac, 1 phase 4 A dc +/-1.0%
AS480 From stator, optional EBS boost 100-264 V ac, 1 phase 5 A dc +/-1.0%
MX341 PMG, 3-phase 190-264 V ac, 1 phase, 2 wire 2.7 A dc +/-1%
MX342 PMG, 3-phase 190-264 V ac, 1 phase, 2 wire 2.7 A dc +/-1% average sensing
MX321 PMG, 3-phase 190-264 V ac, 2 or 3 phase 3.7 A dc +/-0.5% RMS
DM110 PMG or other source, digital PWM Up to 600 V ac, no PT needed 7 A dc 0.5%

Related STAMFORD products: STAMFORD AS480 Automatic Voltage Regulator (AVR), STAMFORD SX460 Automatic Voltage Regulator (AVR), Self-Excited, STAMFORD MX321 Automatic Voltage Regulator (AVR), 3-Phase Sensing, STAMFORD MX341 Automatic Voltage Regulator (AVR), 2-Phase Sensing, STAMFORD MX342 Automatic Voltage Regulator (AVR) with Current Limiting and STAMFORD S0 Low Voltage Alternator 7.5-30 kVA.

Documents and quotation

Seven Star LLC supplies STAMFORD DM110 regulators on request. The bulletin is linked on this page. Send the alternator model, serial number, whether PMG excitation is fitted, and the synchronising or load-sharing scheme in use, such as a Woodward SPM-D10 synchronizing unit. See Diesel Generator Spare Parts for further parts or the Cummins C1000D5B 1000 kVA diesel generator set for a complete set. Confirm revision and software compatibility before ordering.

Datasheets & Documents
  • PDF Datasheet STAMFORD DM110 digital AVR product bulletin (EN, 2 pages) Download
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About brand

STAMFORD is the alternator brand of Cummins Generator Technologies, sold together with AvK as STAMFORD | AvK. Its history starts in 1904 with the Cutting Brothers' electrical engineering business in Stamford, England, later renamed Stamford Electrical. Newage Engineers bought Stamford Electrical in 1950, and Cummins took over Newage with Onan in 1986.

Seven Star LLC, an independent supplier in Muscat, sources these alternators and regulators for generator builders and plant owners in Oman and the GCC.

STAMFORD company profile

Founded 1904, Stamford, England, by the Cutting Brothers
Ownership Cummins Inc., through Cummins Generator Technologies
Sister brand AvK, founded in Frankfurt in 1919 as A. van Kaick
Range Brushless AC alternators from 7.5 to 11,200 kVA
Product families STAMFORD low and medium voltage alternators, AvK alternators for large and medium voltage sets, automatic voltage regulators such as MX341, MX321 and DM110, spare parts

Milestones

  • 1904: The Cutting Brothers start their business in Stamford.
  • 1925: The company is renamed Stamford Electrical.
  • 1950: Newage Engineers acquires Stamford Electrical.
  • 1986: Cummins acquires Onan and with it Newage.
  • 2006: The business is renamed Cummins Generator Technologies.

Alternators and AVRs listed here

The pages cover the S-Range alternators S0, S1, S4, S5, S6, S7K and S9LV, the UC22 and UC27 frames, and the AS480, MX321, MX341, MX342, SX460 and DM110 voltage regulators. Each page carries the ratings and specification from the maker brochure, datasheet or owner manual, including options as printed.

Where these alternators are used

The maker names data centres, marine, telecoms, standby and critical protection, combined heat and power, rail and prime power as typical applications, on diesel and gas engines. In the Gulf these are the same standby and prime-power sets used on camps, plants and pumping stations.

STAMFORD products we list

Family Examples
Diesel Generator Spare Parts AS480 Automatic Voltage Regulator (AVR), MX321 Automatic Voltage Regulator (AVR), MX341 Automatic Voltage Regulator (AVR), MX342 Automatic Voltage Regulator (AVR)…, S0 Low Voltage Alternator 7.5-30 kVA, S1 Low Voltage Alternator 35-62.5 kVA, S4 Low Voltage Alternator 250-450 kVA, S5 Low Voltage Alternator 450-750 kVA and 5 more

Ordering parts and alternators: what we need

For an alternator, send the model, serial number, winding number, kVA, voltage and frequency from the nameplate. For a regulator, send the code printed on the existing board and the alternator model, because the right replacement depends on the excitation system.

Facts checked against the STAMFORD | AvK heritage timeline and Grace's Guide, October 2026.

FAQ

Questions about the STAMFORD DM110 Digital Automatic Voltage Regulator

Answers from our engineering team on installation, compatibility and integration.

01Who makes the DM110?
Basler Electric produces it for STAMFORD and AvK products, as stated in the bulletin.
02What is the output stage?
A 7 A dc PWM power stage, 63 V dc.
03How is it configured?
Through BESTCOMS software on a PC connected to the RS-232 port, supplied on CD.
04What generator size is it for?
Brushless synchronous generators up to 5 MW.
05Which approvals are listed?
cURus per UL 508 and CSA C22.2 No. 14, CE compliant and DNV certified.