Heavy-Duty Incremental Rotary Encoder, 2000 PPR, 2.62 in Servo Mount, 3/8 in Shaft, Complementary A/B/Z Line Driver, 5-28 VDC, 10-Pin MS Connector

What this encoder actually isThe nameplate on this unit reads MOD. NO. H25G-SB-2000-ABZC-28V/V-SM18, PART NO. 01008-1627, S/N MM21059, DATE 07/19/11, VDC IN 5-28. It was built in Goleta, California by BEI Industrial Encoders, now part of Sensata Technologies. Note that this differs from the number the listing previously carried (01002-7811 / XH25D-SS-2500-…); the specification below follows the nameplate, because the nameplate is what ships. Both designations are indexed under Cross-Reference so either search finds this page.

Model code, decodedH25 – Heavy Duty family, 2.5 in body. BEI’s flagship industrial encoder, designed for machine-tool duty rather than light-duty OEM work.G – 2.62 in diameter servo-mount housing. This is a clamp-mounted body, not a bolt-through square flange. You need servo clamps (BEI 31165-001 for 0.093 in grip, 31165-002 for 0.125 in) or a matching servo ring; they are not supplied with the encoder. If your machine has a square-flange pocket, this is the wrong housing – you want the H25D.SB – shielded bearings, no shaft seal. This is the trade-off worth understanding: the H25 only reaches IP66 when it is ordered with the shaft seal, and Sensata’s own datasheet notes the shaft seal is not available on the G housing at all. Shielded bearings buy you the lowest starting torque (1.0 in-oz max instead of 2.5 in-oz with a seal) and the highest usable speed, at the cost of ingress protection. Use it in a dry cabinet or a guarded drive-end location, not in coolant spray or a washdown zone.2000 – 2000 cycles per shaft turn. With complementary quadrature outputs a 4x-decoding counter card resolves 8000 counts/rev.ABZ + C – dual quadrature channels plus a once-per-revolution index, each with its complement: six signals (A, /A, B, /B, Z, /Z) plus supply, common and case ground. A leads B for counter-clockwise rotation viewed from the shaft; the index is a half-cycle Z gated with negative B. The complements are what let a differential receiver reject common-mode noise, which is why this configuration survives long runs in a VFD cabinet.28V/V – line-driver output, 5 to 28 VDC in, output swing equal to the supply. Feed it 24 V and you get 24 V logic; feed it 5 V and you get 5 V logic, so one part number covers both a 5 V counter card and a 24 V PLC high-speed input. The nameplate confirms VDC IN 5-28.S / M18 – side-exit termination on an MS3102R18-1P 10-pin connector. Mating connector is MS3106F18-1S; BEI cable assemblies 31186-1810 / -1820 / -1850 give 10, 20 and 50 ft ready-made.Published performance (Sensata H25 datasheet)Supply current 100 mA typical plus output load, 250 mA maxFrequency response 300 kHz. At 2000 PPR that puts the electrical ceiling near 9,000 rpm, below the 10,000 rpm nominal mechanical limit – so on this resolution the bearings are not what limits you first.Shaft: 3/8 in stainless steel with a 0.75 in long x 0.03 in deep flat; 0.0005 in TIR runout at midpointShaft loading up to 40 lb axial / 35 lb radialBearing life 2 x 10^8 rev at rated load, 1 x 10^10 rev at 10% of rated loadOperating -40 to +85 C; shock 100 g for 5 ms; vibration 50-2000 Hz at 30 grms; humidity 98% RH non-condensingReverse-polarity, overvoltage and output protection diodes fitted as standard – a real advantage on a retrofit where the wiring is being guessed atDie-cast aluminium bearing housing and cover, EMI shielded; 13 oz typicalFitting notesAlways couple a servo-mount encoder through a flexible coupling (BEI 39074-12-12 for 3/8 to 3/8 in) rather than a rigid one – the 0.0005 in runout spec assumes the shaft is not being side-loaded by a misaligned drive. Do not tie line-driver outputs directly to 0 V; the datasheet warns this can damage the driver. If your existing encoder was a sealed (SS) unit in a wet location, treat this as a different animal and add a shield or move the mounting.

Interchange and obsolescenceBEI Industrial Encoders became BEI Sensors and is now Sensata Technologies; the H25 platform ran for decades, so a 2011-build unit like this one is still a straight electrical and mechanical match for earlier and later H25 servo-mount encoders of the same code. Sensata has discontinued much of the legacy H25 catalogue, which is why new-old-stock units on the shelf matter. Same-envelope alternates from other makers are the 2.5 in servo-mount incremental encoders such as Dynapar/NorthStar and Sensata H20/H25 variants – but confirm PPR, output type and connector pinout before swapping, because the MS3102R18 pinout is BEI’s own.

QuantityOne encoder per unit, exactly as photographed. Mating connector, cable, servo clamps and coupling are not included.