What this 3VA1 MCCB carries
The Siemens 3VA1163-5MH32-0BC0 is a 3VA1 IEC frame 160 molded-case circuit breaker in breaking capacity class M, rated Icu=55kA at 415 V AC. It is a 3-pole unit with a TM120M thermal-magnetic trip set to In=63 A, configured for starter protection — meaning it provides short-circuit protection only, with no overload protection element active (the motor starter handles overloads). The adjustable instantaneous trip range is Ii=5...15 x In. This order code includes an undervoltage release (UVR) coil rated 24 V DC, two HQ auxiliary switches, and a nut keeper kit. The UVR trips the breaker on loss of control voltage — common in safety circuits where a downstream contactor or safety relay drops out and needs the breaker to follow.
Breaking capacity and deployment
The 55 kA Icu at 415 V puts this in the M (medium) breaking class — enough for most industrial secondary distribution and motor branch circuits, but not the high-fault class H (100 kA+). On a 400 V panel with a transformer rating under 2000 kVA, this holds selectivity with upstream fuses or a larger-frame breaker. The 3-pole form factor fits standard 3VA1 mounting accessories and busbar adapters.
What the ratings mean for fit
The TM120M trip unit is a thermal-magnetic design with a fixed thermal element (not adjustable) and a magnetic adjustable range of 5–15 x In. At 63 A, that means the magnetic pickup is adjustable from 315 A to 945 A — wide enough to coordinate with motor inrush on a 30–50 hp motor across-the-line start. The 'starter protection' designation (no overload protection) means this breaker sits upstream of a contactor and overload relay; the overload relay handles running overcurrent, and the MCCB handles the short-circuit fault only. The undervoltage release (UVR) at 24 V DC is a shunt-type trip that opens the breaker when voltage drops below roughly 60% of rated. It is not a time-delay UVR — it trips immediately on undervoltage, so it is suited for emergency-stop chains or safety-rated power removal where you want the breaker to drop on control-power loss. The two HQ auxiliary switches provide form-C (NO+NC) contacts rated for standard 24 V DC control logic.