Table of Contents
Advertisement
•
- 3 -
2 •
Description
Relay
75K88
i~
a self contained, single phase overcurrent protec-
tion device with inverse definite minimum time characteristics.
Its applications include primary protection of radial networks
in distribution and industrial installations and back-up protec-
tion for distance relays and similar schemes.
The
7SK88
can be supplemented by the directional relay
7SP88.
This combination provides a directional inverse time protection
system for the protection of ring mains and parallel lines or
transformers.
~
It can be equipped with a high set instantaneous element. Al-
though designed principally for operation from an auxiliary d.c.
power source, a version is available for current transformer de-
rived auxiliary power, allowing use in installations where sepa-
rate d.c. power is not provided.
•
•
3..
Acceptance Check
On unpacking the relay, check the nameplate to ensure that the
model number and rating agree with the requirements. Check that
there are no signs of physical damage. The relay has been tho-
roughly works-tested and calibrated. It contains no moving parts
and is therefore ready for installation without adjustment. If
the target indicator shows "tripped" (red) when delivered, this
is unimportant since it can be reset as soon as the auxiliary
supply voltage is connected or, with the C.T. powered version,
when at least 20
J
load current flows in the primary circuit.
4.
Installation
The case is designed for flush mounting in a panel or support
plate of any convenient thickness (fig. 1) and at any convenient
angle in a location reasonable free from excessive heat, dust
and moisture. It can be secured by two machine screws (H6), with
nuts, top and bottom of the front bezel •
Advertisement
Table of Contents
