Coil Specs & Panel Fit
The Siemens 3RT5944-5AR61 is a SIRIUS magnet coil — the replaceable solenoid that pulls in and holds the contactor armature. It's the part that fails when a coil burns out or the control voltage changes, so this is what you swap to get a contactor back in service without replacing the whole power block. Rated 220 V at 50 Hz and 240 V at 60 Hz AC, with an operating range of 0.8 to 1.1 times nominal at 50 Hz. That means the coil holds in reliably down to about 176 V and picks up cleanly up to 242 V on a 220 V nominal line — useful if your control transformer sags under load or you're feeding from a generator that drifts. Termination is screw-type, so it's a direct drop-in for existing SIRIUS contactor installations that use screw terminals on the coil circuit. No crimping tool change or terminal adapter needed — just land the wires and torque.
Because it's active, the supply channel is the normal Siemens distribution network. No surplus gamble, no broker hunt — just a standard procurement line.
What the Operating Range Tells a Field Tech
The 0.8 to 1.1 operating range at 50 Hz is the voltage band over which the coil will pick up and seal. Below 0.8 × nominal (176 V for the 220 V tap) the coil may chatter or fail to close — that's your diagnostic threshold if you're troubleshooting a contactor that buzzes or won't pull in. Above 1.1 × nominal (242 V) you risk overheating the coil winding. Measure the control voltage at the coil terminals, not at the transformer output; voltage drop across long control wiring is a common miss.