TM500 high-power compartments
The TM504, TM506 and TM5006 each have one compartment that can accommodate high-power plugins.
In the high-power slot, the 25 V transformer windings can supply at least 1 A each instead of 0.5 A.
The +11.5 VDC/17 VAC supply is separate from the rest of the slots and can float, it is rated for ~4 A instead of 1.3 A.
See the TM500 Series plug-in interface for more details.
A metal cover to the left of the backplane connector allows a switch in the rear of a plugin to sense that it is installed in a high-power compartment.
In the other, low-power compartments, a hole in the cover prevents this. Smaller mainframes like the TM503 may have no such covers at all.
High-power plugins
The first compatible plug-in, introduced along with the TM504 and TM506, was the PS505, which must be operated in a high-power slot to deliver its rated 4 A output, otherwise it is limited to 1 A (and the output is not floating).
The PS503A, released a year later, will deliver ±20 V at 1 A in a high-power slot, instead of only 0.4 A.
In the TM5000 series, the PS5010 can make use of the TM5006's high-power slot to provide 0–15 V @ 1.6 A or 15–32 V @ 0.75 A.
Some double-width plugins circumvent the per-compartment power limitation by drawing power from both slots without requiring a high-power compartment.
