Completely Self-Protected Transformer
Completely Self-Protected Transformer transformers are available with a variety of protection options including a MagneX Interrupter, a secondary breaker with weak link for secondary fault and overload protection, a primary weak link fuse, current-limiting fusing for high interrupting ratings and limiting fault currents, and internal or external lightning arresters.
Completely Self-Protected is a protection system for distribution transformers. The CSP protection system protects the transformer from lightning, secondary faults, severe overloads and provides visual warning of abnormal loading conditions.CSP technology allows transformer manufactures to build high performance distribution transformers which mitigate the operation and maintenance problems associated with conventional transformers.
CSP design provides maximum protection against transformer failure and disruptive outages. It also protects you from extra costs of more complicated installation, unnecessary equipment and power downtime.
refer to more details:http://www.cnrockwill.com/article/completely-self-protected-transformer.html