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Military Circular Connector MS90556 straight plug Power Connector
Military Circular Connector MS90556 is Military Power Connector MIL-Spec connectors MIL-DTL-22992 (formerly MIL-C-22992) Class L QPL Qualified Cylindrical Connector. MS90556 is heavy duty waterproof arc quenching and large size cylindrical connector (cylinder connectors) with straight plug designation. For shell finish, shell size, shell/keyway position, insert arrangement and contact type, see MS90556 Parts Number List and and MS90556 identification.

Military Circular Connector MS90556 is highly suitable for industrial or military applications, and designed to meet the demands of heavy power interconnections.
RTI MIL-C-22992 (MIL-DTL-22992) Class L connector line is a power connector with current ratings ranging from 40 through 200 amperes. This type of connector is required for all ground power equipment by MIL-STD-454, and are considered the preferred connector under MIL-STD-1453, which mandates its use in all equipment procured by the military. The selection of military circular Class L power connectors MS90555, MS90557, MS90558 was primarily based on maximum user safety and equipment protection.

Ordering Information

Connectors are supplied with removable contacts. Contacts are supplied unassembled. Also supplied are applicable accessories. Additional contacts may be ordered separately by part number. Connectors may be ordered by RTI part number or we can cross reference the military (MS) part number - RT90556. Please contact us for modification codes. Or

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MS90556 Installation Instruction (PDF)         MIL-C-22992 Class L Parts Number: MS90555 , MS90556 , MS90557 , MS90558

Military Circular Connector MS90556 Mil-C-22992(MIL-DTL-22992) Class L connector
Part Identification:
MS90556 C 44 4 12 S Z
1 2 3 4 5 6 7
1. Connector Designation
MS 90556 Straight Plug
2. Shell Finish
C: Conductive for Grounded Assemblies.
N: Non-Conductive Assemblies. Figure 1.
3. Shell Size (32, 44, 52) Related to current carrying capacity
32 60 amperes
44 100 amperes
*52 200 amperes available C.O.T.S.
4. Shell/Keyway Position
1, 4, 5, and 6 positions are available to prevent cross mating of dissimilar voltages. Figure 2.
5. Insert Arrangement
6. Contact Type
P: Pin
S: Socket
7. Alternate Insert Positioning
Discrimination of 60Hz and 400Hz assemblies is accomplished by alternate positioning of inserts.
Figure 2.
Keyway Position
N designates normal position. Four other positions (1, 4, 5, and 6) of the master key/keyway prevent mating of incompatible voltages. Refer to the illustration above for applicability.
32 MS90556*32 2.250 Table 2 1.8750-16UN 1.750 2.250 8.188 3.562 2.689/2.678
44 MS90556*44 3.000 Table 2 2.3125-16UN 2.250 3.125 2.500 3.531 3.667/3.646
52** MS90556*52 3.500 Table 2 3.0000-16UN 2.875 3.625 3.250 4.016 4.167/4.146
**Check for QPL status before ordering on their lines (we are not QPLd for those sizes yet!).
  • RTI Class L connectors are equipped with arc quenching chambers to minimize damage to cable or connector and reduce the hazard of live circuit rupture to personnel during the most severe field conditions.
  • Designed with a coupling sequence that engages both the neutral and ground contacts before the power contacts.
  • Socket contacts are recessed well within the dielectric face, which represents a dead face to the outside world.
Equipment Protection
  • Connectors are shell polarized (key/keyway) for alternate voltage and phase requirements.
  • Discrimination of 60 Hz & 400 Hz accomplished by alternate nsert positions.
  • Current rating controlled by shell size.
  • Connectors are fully grounded for all AC applications.
Additional Design Features
  • Shells are machined from high strength aluminum and are supplied with conductive or non-conductive finishes.
  • Equipped with necessary seals for waterproofing whether mated, unmatted, capped or uncapped.
  • Crimped or soldered contacts, hand insertable and removable.
  • Quick connect/disconnect for mating and unmating during severe field conditions.
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