Basler Electric EL 200 Minimum/Maximum Excitation Limiter

DESCRIPTION

a. The Basler Electric Minimum/Maximum Excitation Limiter (Model: EL 200 ) performs 0 func-

tions. As a maximum excltation limiter, it senses the field current output Of the voltage regulator

or static exciter and limits the field current tO prevent overheating . As a minimum excitation

limiter, it senses the leading volt-ampere-reactlve (VAR) output 引 the generator and limits

any funher decrease in 0 怡 tion ()s necessary) tO prevent IOSS Of synchromzation and end

iron heating dunng parallel operation.

b. The EL 200 Excitation Limiter has circular characteristic that is compatible with typical genera-

10r reactive capabilities as shown by Figure 1 . 1 

APPLICATION

The EL 200 Excitation Lim1ter can be used with the following Basler voltage regulators and excita-

tion systems: SSR ， XR2001 ， XR2 2 》 xR2003 ， SR-A Series, SR-F Series, SR-E Series SR-H

Series, SSE, and SER-CB. The EL 200 is designed for use on generating systems and can be

used on a synchronous motor or condenser 评 the procedures in Chapter 4 are followed exactly.

Additionally, the Basler Electric EL 300 has been designed to fu 《 fll 《 moSt mOtOr applications

and is preferred over the EL 200 for this type Of appncation.

POWER SUPPLY

a. The EL 200 senses the generator voltage through transformer T2. This transtormer has tapsa

for use with the following input voltages: 90-139. 180-264. 342-528. and 540-660 Vac, +10%, 50/60

Hz.

b. A on Of the transformer (T2) outputfeeds the regulated power supply t0 produce · 14 Vdc

and a . 14 Vdc output for operating the circuitry 、 The transformer (T2) a 0 provides refer-

ence signals to the VAR detector, the watt detector and power the dc transducer (transformer T3).

b. The VAR and Watt Detectors convert the ac inputs tO dc outputs which represent ()y polarity

and amplitude) the VAR and Watt components Ofthe generator output current. The output of 1h9

VAR detector passes through a tapped resistor network (Curve Selector) to the VAR Comparator.

The VAR Comparator makes a comparison Of the Curve Selector output W1th a dc reference

vo 《 tage- If the leading VAR component (generator current) is higher than the reference voltage,

the Comparator outputs a signal through the voltage regulator/exciter that 刂 cause an exatation

limiting and thus, prevent operation outside the limit. This VAR limitlng action would normally

produce a limiting threshold (Refer to Figure 1 一 1 ) that would approach being a horizontal line at the

. 04 to . 0 . 6 per unit level. To produce the desired output culve ， a Watt signal IS passed through

the Forward Watt Amplifier (non-linear) 10 the VAR Comparator. TO assure proper operation ， a

calibration circuit is provlded 巧 set up the proper levels of operation for a wide range input

current levels.

OUTPUT C!RCUiTRY

The output amplifier produces either positive or negative signals tO drive the regulator 0 r exciter (as

required). The polarity of this signalis determined by the appropriate jumpering ofthe A-B Polarity

Fanning Terminal Strip.

OVER-ÉXCITATION LIMITINGD

a. Over-excitation limting provides an initial fast actlng limlt of the current at a pre-selected

high level (allowing for motor-starting, fault clearing, etc.). After a set period of time (Oto 60 sec-onds),

the limit will drop to a lower level to prevent field overheating.

b. The dc current output Of the exciter or regulatorwlll pass through a the dc transducer (T3 ) .

The ac output of T3 will always be proportional tO the input  This ac output is rectified,

adjusted and applied the lnverse Timer.

0 If an inverse time characteristic destred the lnverse Time Adjustment is set for th 巳 desired

time and the Fixed Time Adjustment set counter-clockwise (CCW) 10 zero time- Figure 2 . 2

illustrates the inverse time characteristics for three dlfferent settlngs Of the lnverse Time Adjustment

(fully CW Mid-Range. and fully CCW)

d. If fixed time characteristic is desired or required, the lnverse Timer is set fully CCW tO zero

time, while the Fixed Timer is set the desired time. After the selected timer has timed out, the

e current becomes limited at the delayed threshold limit.