DIN rail mounting protection relays for use in single and three phase systems. Available in 55mm x 112mm or 100 x 112mm DIN rail cases
For over protection, under protection and combined under & over protection available in AC current AC voltage & frequency versions. Millivolt trip, DC voltage trip, Reverse Power, Phase sequence & Phase balance relays also available in our extensive range of protection relays..
The M200-ST3 protection relay is most commonly used to detect the speed of engines used in generating sets. The pick up, situated close to the flywheel, produces a high frequency pulse train which is directly proportional to the number of teeth passing it. The frequency is converted, by the ST3 into a mA signal, that is directly proportional to the rotational speed of the flywheel. The relay provides the user with the following adjustments which allows control of start up, normal running and protects against under and over speeds of the generator.
Adjustment of crank speed is 10 to 50%
Adjustment of under speed is 50 to 100%
Adjustment of over speed is 100 to 133%
A mA output signal proportional to the input frequency
Typical start up is as follows
When the speed of the morot (or as frequency rises) reaches the crank set point, the crank relay energises (disengaging the crank starter) when the under speed set point is reached, the under speed relay is energised. The motor is now in normal running condition with all relays energised. Should an under or over speed condition occur the appropiate relay is de-energised. Two other safety features are incorporated. , if the pick up sensor input lead breaks, the over speed relay will de-energise. The crank relay will only de-energise when the input frequency goes below 20% of the setpoint. The mA signal can be fed to digital or analogue meters scaled in speed, or to provide a control signal to a PLC etc.
5V peak to peak
1000-10000Hz (speed of rotation RPM x number of teeth / 60)
Open circuit protection
Overspeed relay de-energised.
0-1mA = 133% of nominal speed
0.75mm = 100% of nominal speed
Crank 10 to 50%, Under 50 to 100%, Over 100 to 130%
Better than 0.5% of full span
2% (under, over) crank resets at 20% setting
24V ± 20%
Approx 0.5kg. 100mm case
Note: The three relays in this product are single pole changeover, the remainder of specification is under general specifications.
Normal running speed
Number of teeth on flywheel
Magnetic pick up on output volts
10 volt pk-pk
Calibration at temperature other than 23ºC
Setpoints factory set. Specify frequency of crank, under speed and over speed settings required