Description
The ABB PR512/P IEC CB Protection Unit is a self-supplied medium-voltage circuit-breaker protection device designed for switchboard and electrical installation protection. It is part of ABB’s PR512 legacy protection-unit family and is associated with ABB medium-voltage circuit breakers, including the HD4 series. The PR512/P provides overcurrent and short-circuit protection, while versions configured as 50-51-50N-51N also provide two-stage earth-fault protection.
The unit can operate from current supplied by the primary circuit, reducing dependence on a separate auxiliary power supply for its basic protection functions. Depending on the configuration, current measurement can use two or three phase current transformers, with an external toroidal transformer available for earth-fault measurement.
PR512/P
Product Datasheet
| Parameter | Details |
|---|---|
| Brand | ABB |
| Model | PR512/P |
| Series | PR512 |
| Product Name | IEC CB Protection Unit / Self-Supplied Protection Relay |
| Protection Functions | 50 / 51; certain PR512/P versions also support 50N / 51N |
| Application | Medium-Voltage Switchgear and Circuit-Breaker Protection |
| Power Supply | Self-supplied from CT/primary circuit; auxiliary 24 VDC supply can be used for enhanced functions |
| Origin / Place of Origin | ABB; European manufacture depending on production batch |
| Product Status | Legacy / Not Active Product |
| Dimensions / Weight | Configuration-dependent; verify the nameplate and mechanical version before replacement |
| Discontinued | Yes — ABB currently lists the PR512 family as a not-active product |
The PR512/P 50-51 version provides 51 overcurrent/overload protection and 50 instantaneous or delayed short-circuit protection. The expanded PR512/P 50-51-50N-51N version adds 51N and 50N earth-fault protection. ABB documentation specifies selectable protection curves and threshold settings for these functions.
Q&A
Q: Is the ABB PR512/P self-powered?
A: Yes. The PR512 family is designed as a self-supplied protection unit, allowing its basic protection functions to operate from the primary current circuit.
Q: What protection functions does PR512/P provide?
A: The standard 50-51 version provides overcurrent/overload protection and short-circuit protection. The 50-51-50N-51N version additionally provides two-stage earth-fault protection.
Q: Can PR512/P be used with an external toroidal current transformer?
A: Yes. The applicable PR512/P earth-fault configuration can use an external toroidal transformer for homopolar/earth-fault current measurement.
Q: Is PR512/P still an active ABB product?
A: ABB currently identifies the PR512 family as a not-active/legacy product, so compatibility should be checked carefully when replacing an installed unit.
Q: What should be checked before replacement?
A: Verify the complete part number, protection configuration, CT ratio, earth-fault configuration, circuit-breaker type, wiring, and existing protection settings before installation.
